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414 chemical section Professor Armstrong covered a wide range of topics. He charges Ostwald with filling his test tubes with ink; but he himself writes some 35,000 words, going at times considerably beyond the ascertained facta of science, as in discussing "the revolt of women against their womanhood." Dr. A. S. Woodward before the geological section treated paleontological topics and the old age of races largely in the light of American discoveries. Professor A. E. Shipley opened with some references to Charles Darwin, discussed methods of organizing zoology, with its 600,000 known species, and concluded with a discussion of international oceanic research. Sir W. H. White treated the engineering enterprises and commerce of Canada and Great Britain. Professor E. H. Starling applied physiology and biology to sociological questions. Addresses of equal interest were given before the other sections and at four general meetings, the speakers in practically all cases emphasizing those aspects of science which are likely to hold the | attention and affect the conduct of those who are not professionally engaged in scientific work.

As always, the excursions and social, events were arranged in a way that it does not seem possible to rival in this I country. The Canadian government | appropriated $25,000 and the city of! Winnipeg $5,000 toward the expenses. | It is only necessary to mention the excursion to the Rocky Mountains and • the Pacific coast with 150 invited guests. When the association met at Montreal 300 English members attended the Boston meeting of the American Association, but there does not appear to have been this year any concerted effort to bring the foreign men of science south of the Canadian border.

The Rev. T. G. Bonney, the eminent geologist, professor emeritus in University College, London, was elected president of the association for the meeting to be held next year at Sheffield.

the North Pole and flying across the British Channel are sporting events of the first magnitude. They stir the imagination and unite the whole world in healthy interests and generous enthusiasms. They may also be regarded as achievements of applied science. Thousands of workers in the laboratory and in the field have made possible the adventures whose culmination fills the daily papers. To "nail the stars and stripes to the pole," as Commander Peary cabled, or to win for France "imperishable glory" by a flight from Calais to Dover is not in itself a serious contribution to science. But these achievements exhibit in dramatic form the conquest of nature by man which science has accomplished. Perhaps the only facts of considerable scientific interest so far announced in the case of the "dashes" to the pole are Dr. Cook's statement that he discovered land in the extreme north and Commander Peary's sounding which proved that the sea at the pole is over 1,500 fathoms deep. In the main the appeal is to the imagination and it is unfortunate that patriotic enthusiasm has been checked by a certain amount of skepticism in regard to Dr. Cook's exploit. It is certainly unfortunate that Commander Peary should have so expressed himself. From the time of Herodotus it has been the fate of travelers to have their stories questioned. It is to be hoped that Dr. Cook's records may prove entirely definite, so that all doubts may be cleared up. In any case the pole has been reached, and the way has been cleared for scientific exploration in the arctic and antarctic regions.

the last issue of the Professor A. P. Brigham discusses the capacity of the United States for population and places the maximum number of people that can be supported by our resources at 305,000,000. In an


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Rh earlier volume of the (November, 1900) President Henry S. Pritchett predicted, a population of over a billion two hundred years hence and of about twelve billion six hundred years hence. We may agree with Professor Brigham that "population is a vast and wandering theme." It is, however, fascinating and not without practical interest. Emigration laws and even birth rates are not unaffected by such guesses as may be made.

The population of a country is in the main limited by the food supply. Man does not live by bread alone, but his higher needs are increasingly supplied by an increasing population. With a given stock and a given environment the-number of men of genius who add to the social heritage is proportional to the population. Material supplies other than food are needed, but they are not likely to become exhausted. Metals and clays are inexhaustible; the increasing difficulty of obtaining them will surely be met by improved methods. Metals—also wood and even the materials of clothing—can be used over and over again should this become desirable. Fuel, like food, is consumed, but the sun's energy is boundless and means are already at hand to obtain all that may be needed. It is safe to say that the population of the earth is limited only by its food supply.

The area of continental United States apart from Alaska is, in round numbers, two billion acres, of which one half is in farm lands and one fourth under cultivation. Probably three fourths of the total area could be brought under intensive cultivation and made to give fifty bushels of corn per acre or its equivalent. The food value of a bushel of corn is sufficient to support a man for nearly a month, and the product of an acre would about support four men for one year. If one half of the grain were turned into animal food for human consumption, two men per acre could be fed and the country would support a population of 3,000,000,000. Apart from the possible synthetic manufacture of food, it may be regarded as probable that improved agricultural methods will in the course of a century double the present maximum productivity. It should also be remembered that tropical lands are far more productive and under an ideal civilization would export food and import manufactures. The maximum population that might be supported in the United States may, a century hence, consequently be placed at about ten billions.

Such a maximum figure compares with a probable figure somewhat as the theoretically possible efficiency of a steam engine compares with its actual efficiency. But a population of one billion could be supported comfortably. Our present food supply feeds about a hundred million. Better methods would double the production from the area at present under cultivation and less wasteful methods would halve the consumption. If the area under cultivation were increased from 25 per cent, to 62.5 per cent, there would be food for a billion people. Allowing for a reasonable exchange with tropical countries and an ever increasing efficiency in production such a population would have an ample food supply with a reasonable amount of meat and fruit and even as much alcohol, tobacco and coffee as may be desirable for health. Such a population would not mean in any sense living under the conditions of the Asiatics. The more dense the population within the limits stated, the greater would be the per capita wealth. Nor will the country be crowded. Doubtless most of the people would prefer to live in villages or cities and for the quarter that might prefer the country there would be thirty acres for each family. What the actual population of the United States will be a hundred years hence is a very different question. In a state of nature the number of a species may be reduced by enemies or disease, but as a rule they are limited only by the food supply. But with

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416 man a change more significant than any other in history has taken place within the last fifty years. Thanks to the applications of science, the food supply is ever increasing; but the supply of children decreases in an ominous manner. The population of a country is no longer limited by the food supply, but by a conflict between instinct and rationalism, and by physiological fertility under the conditions of modern civilization. It is not likely that the population of any country will ever again be so large as its food supply would support.

record with regret the deaths of Professor Emil Hansen, the eminent physiological botanist of Copenhagen, and Dr. Otto von Bollinger, professor of pathology at Munich.

professor of medical physics at Paris, has been elected president of the French Association for the Advancement of Science for the meeting to be held next year at Toulouse.—At the celebration of the fifth centenary of the University of Leipzig some ninety honorary degrees were conferred, including a doctorate of medicine on Professor E. B. Wilson, of Columbia University, and doctorates of philosophy on Professor Jacques Loeb, of the University of California, and Professor A. A. Michelson, of the University of Chicago.—At its recent celebration the University of Geneva conferred one hundred and fifty honorary doctorates. Among the men of science included were Lord Lister, Professor Haeckel, Professor Ostwald and Professor Engler.

of the University of Michigan, has been elected state geologist to succeed Mr. A. C. Lane, who resigned to accept a chair in Tufts College.—Dr. Juan Guitaras has consented to remain director of sanitation and chairman of the National Board of Health for Cuba, in view of the fact that the government has now appropriated sufficient funds for the work of the department of sanitation.—Dr. E. D. Durand, the director of the census, has announced the appointment of experts in statistics, economics, agriculture and manufactures to cooperate with him in the formulation of the census schedules on which the enumerators will enter the information they obtain next April. The conferees on the agricultural schedule are: Dr. J. L. Coulter, instructor in agricultural economics in the University of Minnesota; Dr. H. C. Taylor, professor of agricultural economics in the University of Wisconsin; Dr. C. F. Warren, Jr., professor of farm management in Cornell University, and Dr. T. M. Carver, professor of economics in Harvard University. The conferees for manufactures and on population are leading experts, being in most cases university professors.

the British are reorganizing the College of Medicine and the Technical Institute at Hong Kong into a university, the Germans have established a school of university grade at Kiao-chau. It is said that the German government has appropriated $160,000 for its establishment and will contribute $50,000 annually for the support of the institution.—The assembly of Iceland has decided to establish a university at Reikjavik, with four faculties and sixteen professors and lecturers.

the will of Cornelius C. Cuyler, the New York banker and a trustee of Princeton University, $100,000 is bequeathed to Princeton University. The residue of the estate, which is said to be very large, will go to the university after the death of Mrs. Cuyler.—The council of the city of Cincinnati has appropriated the sum of $576,000 to erect three new buildings for the University of Cincinnati.


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HE earth has two principal motions, one of revolution about the sun, the other of rotation upon an axis. The revolution about the sun is accomplished in 365 days at an average speed of nineteen miles per second, or thirty-three times the speed of the swiftest modern projectile. The rotation upon its axis is accomplished in twenty-four sidereal hours, and since the equatorial circumference of the earth is nearly 25,000 miles, a point on the earth's equator has a speed of rotation of over one thousand miles per hour.

In form the earth is an oblate spheroid, a flattened sphere, and the axis about which it rotates coincides very nearly with the shortest axis of the body. If a plane be passed through the center of the earth perpendicular to the axis upon which it rotates, not perpendicular to the shortest axis, this plane will cut the surface in a circle which is known as the equator. One of the two coordinates by which the location of a place on the earth's surface is designated is its distance north or south of the equator—measured in degrees, not in miles—and this coordinate is called latitude.

Let the small circle at the center of Fig. 1 represent a section of the earth through the plane of any meridian and the large circle the line in which this plane extended cuts the celestial sphere, supposedly at an infinite distance, P'P" being the direction of the axis upon which the earth rotates and CE the line in which the plane of the equator cuts the given plane. Let O be the place of observation and NS the line in which a plane through the center of the earth parallel to the horizon plane at O cuts the plane of the meridian. According to the definition the arc EO is the latitude of the place O and it is easily seen from the figure that this arc is equal to the corresponding arc on the sky E'Z,


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418 the declination of the zenith—declination being defined in a way exactly similar to latitude, i. e., the angular distance of a point on the sky north or south of the celestial equator. Latitude is usually designated by the Greek letter Φ, and it may be seen from the figure that a third definition of latitude is the angular distance of the celestial pole above the horizon—the altitude of the celestial pole.

Many methods of determining latitude have been devised, some of them coming down to us from the ancient Chaldean and Egyptian astronomers. The simplest method is to measure the altitude of the sun at noon on the day it passes through the equinox. On that day, the sun will cross the meridian at the point E', and its altitude will then be 90° − Φ, as may be readily seen from the figure. A rough value of

this angle may be obtained by measuring the shortest shadow of a vertical stick on a level piece of ground on the day of the equinox. The height of the stick divided by the length of the shortest shadow is the tangent of the complement of the latitude.

If the earth be considered a rigid body and the axis upon which it rotates be fixed within the body of the earth, the latitudes of all places upon its surface will remain always the same. If, however, the axis should shift its position within the earth, then the equatorial plane, which must be always perpendicular to the axis, must shift and consequently the latitudes of all places on the earth's surface must change accordingly.

It is well established that, at least during historic times, no changes of any considerable magnitude have occurred in the latitudes of places on the earth. It has long been suspected by astronomers, however, that


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Rh minute changes of latitude were taking place, but it is only during the last quarter century that the methods of observation and calculation have reached that degree of refinement necessary to detect these small changes.

In 1884 and 1885 Dr. Küstner, astronomer at the Royal Observatory of Berlin, made a series of observations upon certain stars for the purpose of determining the constant of aberration—the maximum apparent displacement of a star due to the finite ratio between the speed of the earth in its orbit and the velocity of light. One of the quantities used in the reduction of these observations is the latitude of the place of observation. Dr. Küstner found his results to be discordant, much more so than he had good reason to believe that they should be from the known care and precision with which the observations were made. Upon investigation it was found that these discrepancies could be almost entirely explained away by assuming a change in the latitude. Dr. Küstner, therefore, in 1888, made the bold announcement that the latitude of the Berlin Observatory had changed during the period over which his observations extended.

This announcement aroused wide-spread interest and steps were immediately taken by the International Geodetic Association to test the reality of the announced variation. Through the cooperation of the observatories at Berlin, Potsdam, Prague and Strassburg, observations for latitude were begun in 1889 and carried on continuously for over a year. These observations agreed in showing a minute but appreciable change in the latitude. In order to test the matter still further, an expedition was sent in 1891–2 to Honolulu, and observations for latitude were made there simultaneously with others made at the observatories just named. As Honolulu is on the opposite side of the earth from Europe, it is seen at once, from Fig. 1, that if the latitude were increasing at the European observatories a corresponding decrease should be shown at the Honolulu station. The results came out as expected and this was generally accepted as a complete demonstration of the reality of this phenomenon. Fig. 2 gives a graphical representation of the results, time being measured along the horizontal and latitude along the vertical line.

The observations thus far made showed that the changes in latitude were periodic in character, that is, the latitude of any place would increase for a certain length of time and then decrease to a minimum value and so on, continuing to oscillate between certain limits. It is easily seen that such changes in the latitude of any place may be


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420

explained through the assumption of a revolution of the axis of rotation about the shortest axis of the earth, or the axis of figure as it is called. In Fig. 3 let PP1 be the axis of figure and P′P1′ the position of the axis of rotation at a time when P and P′ lie in the meridian of the place of observation O, and let E′E1′ be the line in which the plane of the equator cuts the meridian plane of this place. If now the axis of rotation is given a motion of revolution about the axis of figure, then when one half a revolution has been completed the axis of rotation will be in the position P″P1″, the equator line will have shifted to E″E1″, and the latitude of the place O will have changed from E′O to E″O, the whole change in the latitude, E′E″ being 2i, or twice the angle between the axis of figure and the axis of rotation. After a complete revolution of the axis has been accomplished the latitude of the place O will again be E″O and it will oscillate between the maximum value E′O and the minimum value E″O. The reader should bear in mind that the figure is grossly exaggerated, the actual value of the angle i being less than one half of a second of arc. If the angle i remains constant and the axis of rotation revolves about the axis of figure with a uniform speed then the place of observation will apparently swing back and forth in its meridian through an arc equal to 2i. If the


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Rh values of the latitude be plotted along a vertical line and time along the horizontal, we shall obtain the representation of a simple harmonic motion, the crest of the wave corresponding to a maximum value of the latitude and the trough of the wave to the minimum value.

About the time of the expedition to Honolulu, Dr. Seth C. Chandler, of Cambridge, Mass., one of America's foremost astronomers, took up the subject of the variation of latitude and through a brilliant series of

researches, published in the Astronomical Journal, succeeded in setting forth a number of very interesting results. Dr. Chandler examined all the astronomical observations made with transit instruments, meridian circles, zenith tubes and allied forms of instruments, which were at all suitable for throwing light upon the subject. The first and most interesting result obtained by Dr. Chandler was that the period of the latitude variation was about 427 days. He showed that the observations of the eighties and nineties could be represented very well by assuming that the axis of figure of the earth revolves about the axis of rotation in a circle of thirty feet radius in a period of 427 days.

Dr. Chandler's investigations of earlier observations, which run back as far as Bradley's classic observations for the determination of the constants of precession and nutation made with a zenith tube in the early part of the eighteenth century, seem to show that the period of variation was formerly considerably shorter than at present, the observations of the eighteenth century seeming to demand a period of about 370 days. Later observations showed also that the amplitude of the change is not constant, so that the change in latitude can not be accurately represented by assuming that one axis revolves about the other in a circle of thirty feet radius. Chandler's later conclusion is that


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422 the motion of the earth's pole may be conveniently separated into two motions, one an annual revolution in a narrow ellipse about thirty feet long and eight feet wide, but varying in form and position, the other a revolution in a circle about twenty-six feet in diameter with a period of 427 days; both motions being counter clockwise. The resultant of these two motions is quite irregular, as may be seen by referring to Fig. 6, which will be explained later.

From Dr. Chandler's investigations and from the observations for latitude made during the early nineties, it became evident that the movement of the earth's pole was a very complicated one and that an accurate determination of its motion could be obtained only through continuous observations of the latitude at various places on the earth's surface. In 1896 a plan was promulgated by the. International Geodetic Association whereby it was proposed to establish stations for the express purpose of observing the latitude. For reasons to be stated later these observatories were all to be located on the same parallel of latitude and in selecting them, social, hygienic, seismological and meteorological, as well as mathematical, conditions were considered, the prime requisite being, of course, that all of the stations have a fair proportion of clear nights at all seasons of the year. Seventeen different combinations of stations lying between latitudes +36° 48′ and +44° 50′, and including two combinations in the southern hemisphere on parallels −33° 54′ and −33° 27′, were considered. The parallel of +39° 8′ was finally chosen with the stations located in Japan, in Italy and the eastern and western parts of the United States. Two other stations were subsequently added, one in Central Asia and the other in the central part of North America, at Cincinnati.

The preliminary work of establishing the stations occupied about three years and observations were begun at all of them in the fall of 1899. The Japanese station is situated very close to the city of Mizusawa (10,000 inhabitants), which lies in a fertile valley 290 miles north of Tokio. The valley is nearly enclosed by two ranges of mountains, having a general northerly and southerly direction, the highest peak of which is 6,700 feet above sea-level. The meteorological conditions at this station are not especially favorable. There is a large range between summer and winter temperatures and the percentage of cloudiness is greater than at any other station. Nevertheless, the two observers, Dr. H. Kimura, director, and Dr. T. Nakano, observer, who have served continuously since the observatory was established, have obtained a most excellent series of results. The number of earthquakes at Mizusawa is large, but the locality is not affected by these disturbances as much as some other portions of Japan. Since the observatory was established there has been none of sufficient intensity to seriously affect the observations.

The Central Asian station is located in the Russian possessions east


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Rh of the southern end of the Caspian Sea, six miles northwest of the city, of Tschardjui and two miles from the left bank of the Amu Daria, or River Oxus. The observatory is located on an oasis in a sand-waste traversed by many canals. There is a greater range in the annual temperature at this station than at any of the others. Tschardjui is affected by very few earthquakes. The observations at this station are made by a single observer, several having taken part thus far, all of them officers of the Russian army.

The Italian station is very picturesquely located on an old tower, San Vittorio, close to the city of Carloforte, on the island of San Pietro, which lies west of the southern end of the island of Sardinia. The tower is located on a peninsula on the east side of the island, so that the meridian of the observatory lies almost entirely over the Mediterranean Sea, and anomalies in refraction would seem to be absolutely excluded. The island is free from mountains, the highest point being some 650 feet above sea-level. Carloforte has 8,000 inhabitants and can be reached from Cagliari, the chief city of Sardinia, in eight hours. The meteorological conditions at Carloforte are very favorable. The annual variation of temperature is less than at any other station and over 70 per cent, of the nights are clear, a condition which prevails, I believe, in no other section of the world than that surrounding the Mediterranean Sea. The island is free from earthquakes, there having been only four in nearly four hundred years of any considerable intensity, and none of these destructive. The observations at this station are made by two observers, who alternate with the nights. Several changes in the staff have taken place thus far, but all its members have been Italian astronomers.

The station in the eastern part of the United States is located half a mile south of the village of Gaithersburg, Maryland, twenty-one miles northwest of the city of Washington. The surrounding country is hilly, the observatory has an altitude of 540 feet above sea level and the meteorological conditions are fairly favorable. Mr. Edwin Smith, of the Coast and Geodetic Survey, made the observations at this station during the first year; Dr. Herman S. Davis during the succeeding five years. The work is now in charge of Dr. Frank E. Ross.

After the parallel of 39° 8′ had been selected for the location of the latitude observatories it was found that this parallel passed through the grounds of the Observatory of the University of Cincinnati, and Professor J. G. Porter, director of the observatory, volunteered to carry on observations if he were provided with an instrument. The observatory is located on a hill, five miles northeast of the city, and one mile east of the Ohio River. The altitude of the observatory is 800 feet above sea-level and the meteorological conditions are fairly favorable. Thus far all of the observations, except a few during the summer months, have been made by Professor Porter.


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428 Observations would therefore be made at all six stations on the same night on an average of once in every sixty-four nights. The assumption, however, that observations are made upon fifty per cent, of the nights is somewhat in error, the true percentage being almost exactly 46.5. The probability of this event occurring would be therefore ,6 which equals. The event would occur on an average therefore of once in every ninety-nine days, or nineteen times during the five years under consideration. This result is in exact agreement with the observed number.

Let us now ask, What is the probability of obtaining a complete night's work at all six stations on any particular night? The ratio between the number of complete nights and the total of nights is not given in the published results, but is probably not far from one half. At Ukiah about sixty per cent, of the nights upon which observations are made are complete, but the percentage is known to be less at some of the other stations. If now we assume that observations are made upon fifty per cent, of the nights, and fifty per cent, of these are complete, then a process of reasoning similar to that just used will bring us to the result that the probability of the occurrence of the event under consideration is 2 =. That is to say, a complete night's work will be obtained at all six stations on an average, in round numbers, of once in every 4,000 nights, or once in about eleven years, so that it is not at all surprising that this rare event did not occur at all during the first five years of observations.

The observations made during the first five years after the international latitude stations were established, and the results deduced from them, have been published in two quarto volumes. These observations show periodic changes in the latitude similar to those found from earlier observations. The results obtained at the various stations, from the beginning of 1902 to the end of 1905, are represented graphically in Fig. 5, taken from the second volume just mentioned. All the observations obtained at each station during a certain period, about a month, are combined into an average value, these mean results are plotted, and represented in the figure by the small circles. The small figures standing adjacent to the circles indicate the number of


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Rh observations entering into each average. The small circles are connected by straight lines. The smooth curves in each case are obtained by combining, by means of a mathematical analysis, the results at all

of the stations into a general result, and then from this general result computing the variation of the latitude for each individual station. The vertical distance between any small circle and the smooth curve will be, very nearly, the actual error of the average result represented


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430 by the circle. The station where these vertical distances are the smallest will, in general, have obtained the most accurate results. An inspection of the figure shows that the best agreement was obtained at Mizusawa. It is rather significant that at Carleforte, where more than twice as many observations are obtained than at some of the other stations, and the meteorological conditions are exceptionally fine, yet the agreement between the observed and the computed curves is not so close as at some other stations. This is a good illustration of the precept that, in general, little or nothing is to be gained by increasing beyond a certain moderate amount the number of observations made with the same instrument under similar circumstances. In fact it is quite possible that just as good results could be obtained by limiting the number of observations taken at each station to a monthly average of a hundred or thereabouts.

As Tschardjui and Ukiah are separated by nearly 180° of longitude, the curve of the one is almost the counterpart of the other. It may be seen from Fig. 5 that the maximum change in the latitude, during the time represented, is less than 0″.5, which corresponds to about fifty feet on the surface of the earth. The observatory then apparently swings back and forth in the meridian to a distance of twenty-five feet on either side of the mean position.

Having now the actual observed variations in the latitude at six different stations, separated widely in longitude, it is a comparatively simple problem in mathematical analysis to compute what the actual motion of the pole, with respect to its mean position, must be in order to produce the observed changes in the latitudes. If the difference between an instantaneous value of the latitude and the mean value be represented by $$\Delta \phi$$ the rectangular coordinates of the instantaneous pole, with respect to the mean position of the pole, by x and y; and the longitude of the observing station by $$\lambda$$; then the following equation, the derivation of which is given in the review mentioned above, may be written,

Early investigations showed that the observations were not represented to the highest degree of accuracy by this equation and Dr. Kimura, the Japanese astronomer, suggested the addition to the equation of a third term, z, independent of the longitude. The observations are satisfied much better by an equation of this form, and z turns out to be a small variable quantity of an annual period. No satisfactory physical explanation of this term has as yet been given. Several have been suggested, one of which is that perhaps there is a small annual shift in the position of the center of gravity of the earth.

In order to solve the problem connected with this term, two additional latitude stations were established in the southern hemisphere in


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Rh They are both located in south latitude 31° 55'—one at Bayswater, near Perth, West Australia, and the other at Oncativo, in the Argentine Republic, about forty-five miles from the National Observatory at Cordoba. Definite results from these observations have not yet been obtained, but Dr. Albrecht has recently published a short note stating that a provisional reduction of the observations obtained at the two southern stations shows that z has the same sign at the south parallel as at the north, and probably the same magnitude. If this is true the hypothesis of a shift in the center of gravity of the earth must be abandoned. This term is zero about ten days before the equinoxes and reaches its maximum values, −0".048 and +0".044, about ten days before the summer and winter solstices, respectively. These facts would seem to favor the meteorological explanation of origin of this term.

The motion of the earth's north pole, from the time the International Latitude Stations were established in the fall of 1899 to the beginning


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432 of 1907 is represented in Fig. 6 taken from the Astronomische Nachrichten, No. 4187. The large square represents a piece of ground fifty feet on a side. The small circles represent the position of the pole for each tenth of a year beginning with 1899.9 and ending with 1907.0. By starting at the beginning and following out the motion of the pole a roughly spiral path is found with a clearly marked period of about seven years, the position of the pole at the beginning of 1907 almost coinciding with the initial position, 1899.9.

The observations made at the International Latitude Observatories have determined the motion of the pole with a degree of refinement and continuity never before attained, and it is now found that the laws deduced by Chandler fifteen years ago are no longer sufficient to accurately represent the observed motion. Dr. Kimura has recently made a harmonic analysis of the variation of latitude and finds, in addition to the two principal motions of periods of fourteen months and one year found by Chandler, two smaller motions with periods of 0.75 and 0.6 of a year. Kimura also finds that the principal motion of fourteen months is in an ellipse and not in a circle as found by Chandler, the interpretation of which would be, that the equator is an ellipse and not a circle, if we assume the earth to be made up of homogeneous layers, or, in technical language, that the equatorial moments of inertia are unequal.

The change of latitude being so very small is, of course, of no consequence whatever to the navigator who has to determine his position at sea. It is, however, of great interest and importance from a scientific standpoint, and it is hoped that the work at the various stations may be carried on long enough to make a definitive determination of the laws of the polar motion possible, so that a mathematical formula may be constructed from which the position of the pole, or the latitude of any place, may be computed for any time past or future.

One way in which the variation of latitude might have political or commercial significance is in cases where a certain parallel is designated as the boundary line between two countries, states or counties. For instance, the forty-ninth parallel is, for a portion of the distance, the boundary line between the United States and the Dominion of Canada. If any question should be raised, however, a court of arbitration would probably decide that, inasmuch as the actual line shifts its position, the one already established, if not egregiously in error, should continue to be considered the boundary line. A case similar to this has recently been decided by the courts of California. The boundary line between Mendocino and Trinity counties is defined as being the fortieth parallel of latitude. When the counties were first established a surveyor was employed to locate this line, but some score or so of years afterward other surveyors found that the established line lay about two miles too far south. Thereupon Mendocino County brought suit against Trinity


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Rh County to have this two-mile strip taken from the latter and added to the former. After dragging through the courts for a number of years the matter was finally decided in favor of Trinity County, the argument being that, inasmuch as it is impossible, by ordinary processes of surveying, to locate the parallel with absolute accuracy, the original survey, made by due process of law and accepted by both counties, although admittedly largely in error, should remain the official boundary line. The amount of territory, mountainous and sparsely settled, is a comparatively small part of either county, Mendocino County being nearly as large as the state of Connecticut. The question was, however, of considerable importance to the property owners of the two-mile strip. After the land was claimed by Mendocino County, it was assessed and taxed by both counties, and the taxpayers who cast their lot with Mendocino County now have several years of back taxes to pay in Trinity County.

Doubtless most of the readers of this article have already wondered what may be the cause of the shifting of the earth's axis. In 1765, Euler, a famous Swiss mathematician, demonstrated, as a proposition in dynamics, that if a free rigid oblate spheroid rotates about an axis which differs slightly from the axis of figure, or shortest axis, then the axis of figure will revolve about the axis of rotation in a period the length of which will depend upon several factors. He computed that, if the assumed conditions obtained for the earth, then the period of revolution of the axis of figure about the axis of rotation would be 306 days. Obviously, however, the earth is not rigid; the oceans are quite plastic and the ground itself is possessed of some elasticity. Professor Newcomb computed some years ago that, if we assume the earth as a whole to possess the rigidity of steel, then the period of revolution of the one axis about the other would be 441 days, as against 306 days found by Euler on the assumption that the earth is perfectly rigid. The actual observed period is fourteen months, or 427 days, and the legitimate conclusion to be drawn is that the earth as a whole is somewhat more rigid than steel—a conclusion that agrees with that derived by Lord Kelvin and others from entirely different considerations.

Now the question arises, Why does the earth not rotate upon its shortest axis? The explanation is simple. If the earth ever did rotate upon its shortest axis it could not continue to do so because of the shifting of matter upon and within the surface. Winds, rains, rivers and ocean currents are ceaselessly transporting matter from point to point, and during the winter great masses of snow and ice accumulate in the temperate and frigid zones only to disappear again in the summer. Although these effects will, to a large extent, neutralize each other, the sum total can not be other than to produce at least a theoretical lop-sidedness to the earth; and as soon as this takes place there must be a shifting of the axis of rotation. The time of revolution of


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434 the one axis about the other could be accurately computed if the exact form of the earth, the structure of the earth's interior and its coefficient of elasticity were known.

In addition there are other phenomena, namely, volcanoes and earthquakes, through which considerable quantities of matter may be displaced. That the amplitude of the polar motion might be affected by earthquakes was pointed out by Professor Milne ten or fifteen years ago and a French scientist has more recently compiled a table showing the number of severe earthquakes each year and the amplitude of the polar displacement. A rough proportionality between the two seems to exist, that is, the greater the number of earthquakes each year the greater the amplitude of the polar displacement. Such results, however, are to be taken with several grains of allowance. The term "severe earthquakes" is rather indefinite and by modifying its definition quite a variety of results may be obtained from the given data. It might be pointed out that in 1906, the year of the great earthquakes in California and Chile, the amplitude of the polar displacement was small.

We have then a rational explanation of the phenomenon of the variation of latitude. The axis upon which the earth rotates is not in exact coincidence with the shortest axis; such being the case, according to the principles of dynamics, the axis of figure must revolve around the axis of rotation giving rise to the changes of latitude. But on account of the changes incessantly taking place in the distribution of matter upon the earth's surface, and perhaps also within the surface, the amplitude of the polar displacement, and perhaps the principal period of revolution of the one axis about the other, are changeable, the changes taking place in a rather complicated way according to laws as yet not fully determined.

In connection with this explanation we should not lose sight of the fact that all the material moved through meteorological, volcanic and seismic agencies is probably almost infinitesimal as compared with the total mass of the earth, and no one, so far as I know, has as yet shown that the shifting masses are sufficient in magnitude to properly account for the observed annual and other unexplained components of the polar motion.

Indeed, if one desires to follow the path of least resistance, he might abandon the above explanation altogether and adopt the one given by a colored preacher living in the oil region of Texas, who met some brethren at the corner grocery one day and delivered himself of the following explanation of this puzzling scientific phenomenon:


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Rh and spreads apart slightly, so that a few seeds are easily shaken out by a gust of wind. The inflorescence, though dead, may stand for a year or more, and the seeds that it bears may be scattered over a wide area.

Before this plant comes into bloom the tender apex of the short stem is often used as food. Out in isolated places among the mountains one may come upon a rude circle of heavy stones bordering a shallow pit. The Mexican would say that here they were preparing quiote by taking the hearts of the magueys and roasting them in the pit. Upon further inquiry he will say that these morsels are covered with earth and stones and the fire built over them and kept for some hours. The older leaves yield a fiber for cordage, though this plant to a less degree than its larger relative, A. americana. Many uses are found for the maguey; in fact hardly any other plant of Mexico serves the people in so many ways as this one. It provides food and drink, it yields fine strong fibers for ropes, fabrics and other articles. It has served in the manufacture of paper and enters into the construction of fences and buildings. It formerly found use in religious rites and was part of the material of weapons.

As ornamental plants the cultivated magueys are hard to beat. During its fifteen years' or more life it produces relatively few leaves, but towards the close of its span of years one hundred or more of these may be in evidence, each somewhat narrow, six to ten feet in length and often weighing as much as one hundred pounds. Most of them are a dull dark green, some are margined with yellow or yellowish green. They are often planted as hedges or borders, and as such they are very attractive to look at. The short stem which in all the years has not attained a height of two feet now suddenly shoots up to thirty feet, its outstanding branches in symmetrical order enhancing its dignity and beauty beyond that of most other plants.

On the slopes of many foothills that rise from the edge of the desert plain and often on the higher slopes in great profusion, one finds a stately plant which is always conspicuous and always beautiful. Something about the sotól makes it especially attractive, with its pale green leaves an inch wide and a yard long, the tips of which often overtop a man's he.ad. But these leaves, though beautiful to look upon, are well armed against any invader by means of many forward set teeth along their margins. In fact, a leaf of Dasylirion is like a piece of doublee-edged band saw.

Under the hot sun of May and June the flower stalk ascends from the center of the crown of leaves and carries its topmost flowers to twice the height of the horseman riding by. These flowers, unlike those of the maguey, are small and borne on a long and slender, though compact panicle; they are monœcious, therefore not all the tall stems


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are destined to bear the small triangular fruits that often remain the following winter on the stalk that bore them.

This plant, besides being one of the most attractive of the whole desert flora, is not without its uses, both legitimate and otherwise. From the leaves of sotol the natives weave mats and various other articles of utility. They split the long leaves into narrow strips which they weave into hats. But this plant, like the maguey, also furnishes food and drink. The central cabbage-like bud is cooked and eaten. This central bud, and the thick top of the stem below it, are used much in the manufacture of a fiery liquor called Sotól, of rank intoxicating power.

While the plants above cited are striking and characteristic features of this desert vegetation, yet even more common and more characteristic of deserts in general are the cacti, which abound in species and individuals. Cactus, Echinocactus, Cereus, Echinocereus, Mamillaria and Opuntias of both divisions are everywhere. Down on the open plain the nopals (Platopuntias) abound, as one soon discovers who tries to ride across country. The broad flat joints of these plants are everywhere. Here and there a cluster of bisnaga colorada (Echinocactus pilosus) shows the top of its cylindrical body bristling with red spines above the low bushes, for this bisnaga, as the native calls it, does not grow very tall, five feet being about its maximum. It blooms in June and successions of yellow fruits follow the flowers. These lemon-yellow fruits about the size of a lime are possessed also of the lime's acid


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Rh properties. But this plant is not content with the lowlands, but climbs to the top of the mountain above, where I saw some of the largest of its kind.

Echinocactus ingens, like nearly all of the cacti of this desert, prefers the hills, and there its thick trunk, bristling with long straight spines, grows to a diameter of a barrel and as much as five feet in height. This bears its flowers in a furrow across the top. The pulp of this plant is said by the peons to be sweet, but one who has* tasted other cacti which they eat, may be content to leave the appraisal of this delicacy to others.

The opuntias which cover the plain and mountain are of abundant interest in their variety and numbers. The cylindropuntias abound in forms of cholla, cardencia and tazajillo, according to native terminology, with spines long and sharp and barbed, which penetrate with ease thick leather leggings, and where they stick they stay. In this the tazajillo, which grows as high as a horse's back, is especially to be dreaded, with its stiff slender spines; it separates its joints at a touch and sends them along with the passer-by. Under and around these plants scores of these joints are busy taking root, though one seldom finds thickets of tazajillo. Few of these young plants really have a future before them, though there are enough of them as it is. But the cardencias, arborescent opuntias like the species mammilata, spinosior, etc., of the Arizona desert, are not so savage as the cholla, nor so unexpectedly met with as their more slender and less conspicuous relatives, the tazajillos, as above described. In its varied forms the nopál, or flat-jointed Opuntia, is of more interest to the native than all the other cactus forms. This is about the only kind of cactus that may serve as fodder for cattle, and it is a common sight to behold some hundreds of pounds of one of these species carried on passing ox-carts. At the last camp where these travelers rested one could probably find the remains of a fire where they had burned off the spines of a number of nopals, which indeed is the principal diet of their oxen.

Some of these nopáls are of imposing size and aspect, but mostly they are low procumbent forms, branching out in all directions, pushing forth segment after segment from the lower forward margin of the laterally compressed joint. Along the upper margin occur the flowers and the succession of fruits in varying shades of yellow and red. Here and there at higher altitudes are forms which produce edible fruits not unlike the edible tunas which are produced under cultivation. It seems quite possible that these may be the forerunners of some of the cultivated varieties, inasmuch as the preponderance of evidence points to Mexican origin for the tuna-bearing nopáls. Again we find on the hills a small and compact species which has little to recommend it. This, Opuntia microdasys, has branches closely set with coarse spicules which are easily detached and are said to be a frequent cause of blindness


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among horses and cattle. The animals nosing about among the branches of this plant for some tuft of grass or other morsel, dislodge the glochids and get them in their eyes. Every well-appointed dooryard or garden has one or more species of the cultivated cactus which produces edible fruits of which the Mexican is very fond. These are of many varieties, differing in the characters of the branches and the fruits, the latter varying in color from the deepest red to lemon color and in form entirely distinct. They form a very important item in the short list of foods upon which the poorer classes live.

In this desert region one can not but be impressed with the number and variety of the woody plants, shrubs and small trees, which are to be seen on every hand. Many of these are common in our own southwest—mezquite, ocotillo, creosote bush, Ephedra, Condalia, Koeberlinia, species of Atriplex and Acacia are among the most conspicuous, some are the same species and others different, and the less obvious things are, Lippia, Buddleia, Mortonia and many others. In all these the families of the Leguminosæ, Labiatæ and Compositæ are especially prominent, as they are elsewhere in desert regions. The shrubby growth gives color to the landscape, and in many places its whole aspect and character is due to these plants more than to the yuccas, agaves or cacti. Very few trees in this desert are more than fifteen feet high and the majority of them are much less, so that in no sense does the country seem wooded, except upon the highest ranges where pines and oaks occur.

Among these desert shrubs are some of unusual beauty. There is


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Rh Cassia wislizeni, quite common, a tall graceful bush with large panicles of orange-colored flowers, a plant which might well be valued by horticulturists of the north. All through July and August these delight the eye and stand out in conspicuous contrast with the surrounding vegetation. Pinacate they call it, though the reason is not obvious. Again if we walk out over the lower slopes not far from the banks of some arroyo we may come upon the beautiful "huisache," Acacia farnesiana, in full bloom if the time is summer. This plant with its small delicate leaves, its white spines, its little balls of yellow flowers scattered in profusion along the younger branches, is a beauty to behold, but the casual passer-by, if insensible to the beauty of the flowers, may perchance be attracted by their sweet and delicate perfume. Farther along in a shallow wash where the waters occasionally take their way from the higher land, appears Chilopsis saligna in slender graceful form, swaying to every breeze. Its clusters of red flowers need not be seen to be aware of their presence, for their sweet fragrance is borne on the breezes far beyond that of most flowers. There are few desert flowers equally conspicuous in color and perfume, and few as well supplied with either as the desert willow. But where the way leads down into the bottom of the arroyo, almost hidden under the overhanging bank, one comes unexpectedly upon the beautiful "tronadora," to use its Spanish name. Few plants of the desert are more striking in their beauty than this, with its dark, deeply compound leaves and its conspicuous cluster of orange-colored flowers, which reminds one in their form and attitude of those of the trumpet-creeper, and well it may, for it is Tecoma starts, a member of the same genus. If we thread along still further through the tangle of "charnís" (Forrestiera) with its load of mistletoe, and "junco" (Holacantha) and "huisache," with lacy trimmings of the vine, Nissolia, where the dry stream bed is flanked by Trixis, and sometimes Tatalencho (Gymnosperma) on upward to where the steep banks of the arroyo give way to less precipitous rocky slopes and into the deeper cañon beyond, Asclepias linaria springs from the sandy wash at our feet with its sheaf of slender stems, each capped by its umbel of white flowers. Now just to the right where a limestone cliff faces the north and receives little light from the sun that scorches the ground just beyond, is a patch of resurrection plants with their star-like forms expanded to full view by the moisture acquired from the recent shower. The day before when we passed this same way these plants had coiled themselves together into compact balls and were hardly visible in the crevices of the rock. But with the drenching shower came the resurrection to renewed activity. Near at hand some shrubs are covered with a furry growth of grayish grassy-looking plants, which upon nearer approach are seen to be a dense growth of Tillandsia recurvata, a sort of Florida moss, which finds in the moister air of the canon floor or the


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450 mountain top the conditions favorable to its growth and it attaches indiscriminately to any woody plant that furnishes a convenient hold.

But of the many things that we brush by in this ramble we have not the time to tell, but in this narrow space of moisture between zones of perennial drought, occur ferns of the genera Pellæa, Notholæna and Cheilanthes. Under the neighboring rocks their prothallia are growing, and young sporophytes of all ages are coming on. Climbing out of the bed of the cañon in a few steps we find ourselves again among the ocotillos and the agaves and the cacti.

Among the shrubby plants none are so important as the guayule, the native name for Parthenium argentatum. It is one of the most abundant of all the desert plants, especially on the limestone slopes, and its grayish color gives a distinct character to the landscape where it abounds. A small shrub or dwarf tree, it seldom exceeds four feet in height or a stem diameter of four inches. Its leaves are covered with silvery hairs and its flowers are in inconspicuous heads of composite structure not over one fourth inch across. Its light seeds—one hundred would not fill half an ordinary thimble—are supplied with a papery bract by the aid of which they are driven easily by the wind. Maturing in late summer and autumn, the seeds are dropped to the ground beneath the parent plant, or by some strong gust of wind are borne to a distance, where some find lodgment in a sheltered spot—a crevice of the rock or the cover of some friendly shrub. Here, when the rain comes, it is kept moist for time enough to send down a long, slender, thread-like root before drought again overtakes it. After the fitful showers of summer have passed a long dry season awaits the young plant, so it behooves it to make as much root as possible while the growing conditions are favorable. These slender roots will make a growth of six inches in about a week, before the first true leaf has appeared lifted on the short stem half an inch high, and in six weeks the tap root has been observed fifteen inches long. Thus the plant insures itself against the dry season, and by hardening its stem and leaves, makes still further provision against the vicissitudes that await it.

And this example serves, doubtless, for many other desert plants. We find that the seedlings spring up in abundance under the shelter of bushes and cacti and other perennials. In fact, elsewhere there is almost no chance for the survival of a tender seedling, since the hot sun dissipates so quickly the moisture of even a heavy rain that the surface of the soil is again dry in less than a day. The chances of survival of a seedling are exceedingly remote, and considering the great number of seeds produced and distributed, probably only a very small fraction of one per cent, even germinate.

But interest in this guayule which covers the desert slopes is not alone in relation to its environment, but in the hule or gum which it produces, forming no small part of the rubber production of


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Rh. Two and a quarter millions of dollars' worth of this product came from one district in one year recently and much more is following. Back in the middle of the eighteenth century it was discovered that the source of the rubber in the balls with which the Indians were wont to amuse themselves, was this guayule. As the Indians formerly did, so one now may extract this rubber in the same crude way by chewing the bark and rejecting the fiber until sufficient gum for the purpose has been accumulated.

That this gum is a by-product in the physiological processes of the plant and stored in its tissues in the form of granules, is not the least of its interesting features, for most of the rubber-bearing plants known to the public are trees yielding a milky fluid from which the rubber is obtained by coagulation. But in this case the rubber is not obtained by tapping, but by the immediate destruction of the plant.

Besides the mesquite and the greasewood and other shrubs that clothe the valleys and lower slopes, the steeper acclivities abound in Jatropha, Buddleia, Salvia, Bahia, Ephedra and many other woody plants, members of other genera to the number of a hundred or more, are scattered among the agaves, the palmas and the cacti up and down the mountainside.

One who has not sought these plants where they grow can have little idea of their number and variety, nor of their varied structural and physiological attributes which make for complete fitness in the stern environment of the desert. Here they grow and flourish where it would seem there is no chance for life. But they thrive in these barren wastes—league on league of plain and mountain, where there is neither spring nor pool nor forest shade, blistering heat and glare above and hot dry stones beneath, and find it sufficient.


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HE lecturer began by stating, that, although the theory of Darwinism is one of the most simple of comprehension in the whole range of science, there is none that is so widely and persistently misunderstood. This is the more remarkable, on account of its being founded upon common and universally admitted facts of nature, more or less familiar to all who take any interest in living things; and this misunderstanding is not confined to the ignorant or unscientific, but prevails among the educated classes, and is even found among eminent students and professors of various departments of biology.

Darwinism is almost entirely based upon these external facts of nature, the close observation and description of which constituted the old-fashioned "naturalists," and it is the specialization in modern science that has led to the misunderstanding referred to. Those who have devoted years to the almost exclusive study of anatomy, physiology or embryology, and that equally large class, who make the lower forms of life (mostly aquatic) the subject of microscopical investigation, are naturally disposed to think that a theory which can dispense with all their work (though often strikingly supported by it), can not be so important and far-reaching as it is found to be.

Coming to the first great group of facts upon which Darwinism rests, the lecturer calls attention to the great number of distinct species both of vegetable and animal life found even in our own very limited and rather impoverished islands, as compared with the more extensive areas. Great Britain possessed somewhat less than 2,000 species of flowering plants while many equal areas on the continent of Europe have twice the number. The whole of Europe contains 9,000 species, and the world 136,000 species already described; but the total number, if the whole earth were as well known as Europe, would be almost certainly more than double that number or about a quarter of a million species. The following table, showing how much more crowded are the species in small than in large areas, was exhibited on the wall. It affords an excellent illustration of the fact of the great intermingling of species, so that large numbers are able lb live in close contact with other, usually very distinct, species.


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1533.] not know whether they were tortured, whether they confessed, or what they confessed; but we may naturally connect this letter, directly or indirectly, with the events which immediately followed. In the middle of November we find a commission sitting at Lambeth, composed of Cromwell, Cranmer, and Latimer, ravelling out the threads of a story, from which, when the whole was disentangled, it appeared that by Queen Catherine, the Princess Mary, and a large and formidable party in the country, the King, on the faith of a pretended revelation, was supposed to have forfeited the crown; that his death, either by visitation of God or by visitation of man, was daily expected; and that whether his death took place or not, a revolution was immediately looked for, which would place the princess on the throne.

The Nun of Kent, as we remember, had declared that if Henry persisted in his resolution of marrying Anne, she was commissioned by God to tell him that he should lose his power and authority. She had not specified the manner in which the sentence would be carried into effect against him. The form of her threats had been also varied occasionally; she said that he should die, but whether by the hands of his subjects, or by a providential judgment, she left to conjecture; and the period within which his punishment was to fall upon him was stated variously at one month


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Rh and it was at such times that the enormous population of most species and their wide range over the whole continents, always secured the preservation of considerable numbers of the best adapted in the most favored localities. Then the rapidity of multiplication came into play, so that in two or three years the population of each species became as great as ever; while, as all the least favorable variations had been destroyed, the species as a whole had become better adapted to its environment than before the almost catastrophic destruction of such a large proportion of them.

It is the fact of the adaptation of almost all existing species to a continually fluctuating environment—fluctuating between periodical extremes of great severity—that has produced an amount of adaptation that in ordinary seasons is superfluously complete. This is shown by the well-known fact that large numbers of adult animals that have not only reached maturity but have also produced offspring and successfully reared them, continue to live and breed for many years in succession, although varying considerably from the mean, while almost the whole of the inexperienced young fall victims to the various causes of destruction that surround them.

The next subject discussed was the complex nature of adaptations in many cases, and probably in all; a subject of great extent and difficulty. The lecturer directed special attention to the relations between the superabundance of vegetation in spring and summer, the enormous, but, to us, mostly invisible, hosts of the insect tribes which devour this vegetation, and the great multitudes of our smaller birds whose young are fed almost exclusively on these insects. Without these hosts of insects the birds would soon become extinct; while without the birds, the insects would increase so enormously as to destroy a considerable amount of vegetable life, which would, in its turn, lead to the destruction of much of the insect, and even of the highest animal groups, leaving the world greatly impoverished in its forms of life.

The vast numbers of insects required daily and hourly to feed each brood of young birds was next referred to, and the wonderful adaptation of each kind of parent bird which enables it to discover and to capture a sufficient quantity immediately around its nest, in competition with many others engaged in the same task in every copse and garden, was next pointed out. The facts were shown to involve specialities of structure, agility of motions, and acuteness of the senses, which could only have been attained by the preservation of each successive slight variation of a beneficial character throughout geological time; while the emotions of parental love must also have


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456 been continuously increased, this being the great motive power of the strenuous activity exhibited by these charming little creatures.

As illustrating the strange and almost incredible misconceptions prevailing as to the mode of action of natural selection, the lecturer quoted the following passage from the late Lord Salisbury's presidential address to the British Association at Oxford in 1894. After describing how the diverse races of domestic animals have been produced by artificial selection, Lord Salisbury continued thus:

Here we have the extraordinary misconception presented to a scientific audience as actual fact, that advantageous variations occur singly, at long intervals, and remote from each other; each statement being, as is well known, the absolute reverse of what is really the case. It totally ignores the fact, that every abundant species consists of tens or hundreds of millions of individuals, and that as regards any faculty or quality whatever, this vast host may be divided into two portions—the less and the more adapted—not very unequal in amount. It follows that at any given time, in any given country, the advantageous variations always present are not to be counted by ones and twos, as stated by Lord Salisbury, but by scores of millions; and not in individuals widely apart from each other, but constituting in every locality or country, somewhere about one half of the whole population of the species.

The facts of nature being what they are, it is impossible to imagine any slow change of environment to which the more populous species would not become automatically adjusted under the laws of multiplication, variation and survival of the fittest. Almost every objection that has been made to Darwinism assumes conditions of nature very unlike those which actually exist, and which must, under the same general laws of life, always have existed.

The phenomena of protective coloration and mimicry were very briefly alluded to, both because they are comparatively well known and


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Rh had formed the subject of previous lectures; while they are very easily explained on the general principles now set forth. The explanation is the more easy and complete, because of all the characters of living organisms, color is that which varies most, is most distinctive of the different species, and is almost universally utilized for concealment, for warning or for recognition. And further, its useful results are clear and unmistakable, and have never been attempted to be accounted for in detail by any other theory than that of the continuous selection of beneficial variations.

The subject of the dispersal of seeds through the agency of the wind, or of carriage by birds or mammals in a variety of ways, and often by most curious and varied arrangements, of hooks, spines or sticky exudations almost infinitely varied in the different species, was also briefly treated, since they are all readily explicable by the laws of variation and selection, while no other rational explanation of their formation has ever been given.

In concluding, the lecturer called attention to a series of cases which had shown us the actual working of natural selection at the present time. He also explained that these cases were at present few in number, first, because they had not been searched for; but perhaps mainly, because they only occur on a large scale at rather long intervals, when some great and rather rapid modification of the environment is taking place.

In the following paragraph he endeavored to summarize the entire problem and its solution:


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UR chapter of Sigma Xi has recently invited to its membership some two score persons who have shown themselves to be possessed of such talents and aspirations as the society honors and rewards. Of these new members many have finished their preparatory studies, and are entering upon the independent work of science. It is therefore suitable upon this occasion that we should consider some one of those qualities that distinguish the person who is engaged in the scholarly pursuit of knowledge. The quality which I have selected is the possession of temporal or historical perspective; and I propose to use, by way of illustration, the subject of mental inheritance.

Nothing is easier than to exalt beyond its due the present moment. The present is so vivid, so impressive, so intimate, so important for action, as to compel attention; and current means of communication succeed so well in bringing distant lands and deeds within our field of vision that the whole world contributes to the fascination of the passing scene. We all realize this fascination, however much we may set our faces against the vulgar homage paid to the latest mode, the most recent invention, or the last political experiment. We realize it, and, if we are wise, we perceive that the philistine passion for being "up-to-date" (as the street-phrase has it) contains an element of great value—the element of enthusiasm. Scholarly work demands enthusiasm, and every epoch of science has, and, I suppose, will have, its sanctions and its rewards for enthusiastic endeavor. In this regard our own time certainly is not wanting. At a period when the constitution of matter and its elementary forms have, by the discovery of new facts, been brought to the focus of attention; when the development of living forms through their various stages of growth is observed by methods undreamed of by the earlier historians of nature; when the study of evolution has advanced to the stage of analysis and experiment; when the earth is revealing significant traces of primitive man and his works; when psychology proposes new methods for the study of thought and action and for a comparison of the human with the animal mind; when, finally, philosophy rests less upon the authority of great names and systems than upon the immediate data of experience, no ardent novitiate in science can complain that fate has thrown him upon an age of


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Rh platitude and dogma, or has denied to him the opportunity of spending his energies in the cultivation of a land of promise.

The kindling enthusiasm of the man of science must not, however, be confused with the philistine's boast that history is a wreck from which only he and his time have been saved. Opportunity which inspires the scholar inflates the time-server and intoxicates the anarchist. The difference between these persons rests at last upon temporal perspective, or the want of it; for it is the apprehension of new opportunities and new needs in the light of old accomplishments that leads to profitable reconstruction of human knowledge. In mechanical invention, the new model may cause the old to be cast upon the rubbish-heap; but in man's interpretation of the world, old theories and old points of view which have served their generation are never discarded; they still mark the stages of human acquisition and take their place in the development of science. Without a knowledge of them, and of their relation to present problems, no man, however ingenious or fertile, should hope to do more than a journeyman's work in the free advancement of learning.

But even when we know the general history of thought and the special histories of our own small divisions of human knowledge, we are apt to overlook the fact that, in a large sense, civilization itself is a matter of the moment, which may be viewed in the light of a broader perspective. Civilization we measure by hundreds and thousands of years. For example, we trace the Mediterranean cultures eight or ten or twelve thousand years, and then we lose the thread; but the whole history of man we reckon in geological epochs. We find his footprints stamped everywhere upon the Quaternary earth, and we find what appear to be vestiges of him in the deeper deposits of the Tertiary. Throughout the brief day of his written history we study him in a long series of related disciplines which we call "the humanities"; while we hand over the unmeasured period of his whole antecedent career to the single science of anthropology. We glance with admiration at his morning work in iron and bronze and brass, his noontime of Athenian culture, his late hours of reflection and invention, and we seek however feebly to illumine the night of his future; but we tend to overlook the antiquity of man, the record of other days and years, and to avoid the question whether civilization is not, after all, still in the experimental stage—whether we ourselves are not next-door neighbors to the barbarian.

When we regard the rapid accumulations of a few thousand years of culture, we realize that civilization lays upon the human mind a staggering load of traditional knowledge and traditional duty. In "Darwinism and Politics" the late Professor Ritchie has defined civilization as "the sum of human contrivances which enable human beings


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460 to advance independently of heredity." Contrast man and other animals. The animal carries over from his parents and from his racial stock the physical equipment and the functional tendencies which enable him to fight the battle of life precisely as his ancestors fought it. If his type varies under natural conditions, it varies so slowly that, as a rule, many generations are required to disclose the change. With man all this is different. As I just now observed, nurture is cumulative. Each succeeding generation takes up its heritage, not where the preceding generation began, but where it left off. Each has to advance by first absorbing the new attainments of its immediate ancestors. In a real sense, therefore, because he has language and books and institutions and traditions, man is

Notice, however, that man comes into his social heritage only by acquisition during his individual life, by his own individual efforts. Is he, now, as a conscious being, better and better endowed as time goes on for the process of absorption? Does talent grow as knowledge grows? Does mental capacity keep pace with social accumulation? May we not suppose that the men and women of some distant glacial age, who dwelt upon the ice, wore the skin of the seal, and ate raw fish, had as much brain and as generous a measure of talent as have their remote descendents who wear sealskins, and eat ices and caviare? We can not say that they had not. On the contrary, our records, so far as they go, indicate that the social heritage has outstripped the hereditary growth of mind—that, as regards mental endowment, we begin very much as our distant forbears began; only, we proceed at once to burden ourselves with information and obligation which for them did not exist. To compass languages and sciences and histories and arts, and a complicated social and political regime, we are supplied with virtually the same minds that primitive man used for his primitive wants. Is it any wonder, then, that education is the central problem of an advanced civilization?

The question has been raised, however, whether it is not time to look beyond education to the possibility of improving the human stock; whether education is, after all, the only way of civilizing the individual. When the garden vegetable or the domestic animal fails to meet our needs, we improve its breed—so the argument runs; we breed for size, for strength, for flavor, for color, for endurance, for speed, or for general service. When we find that the part of our human stock which is best fitted to carry the cumulative load of civilization is weak, or degenerate, or inclined to sterility, why do we not look to the improvement of those strains that are mentally fittest and to the elimination of the bad? The argument, you observe, assumes that mental endowment and mental capacity are heritable possessions. Is the


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Rh warranted? We can not say until we have examined the present status of the problem of inheritance; but whether or not we are pessimistic as regards the future of the race, we must agree that the sudden and increasing burden which culture places upon the human mind raises this problem to the first rank of importance.

Suppose that we look, then, at the grounds of belief in the hereditary transmission of mind. The belief itself stands among the feed convictions of common sense. In our every-day thinking we take it for granted. The child, we maintain, inherits its father's bad temper just as it inherits its mother's good looks. We consider twice before we adopt the foundling, which may be of dull or vicious parentage. We shake our heads over the wayward son, remembering that his father "sowed his wild oats," and we observe "like father like son," or "blood will tell." We expect to find talent in the children of the gifted, thrift or dwarfed intellect or high purpose, according as these qualities are "bred in the bone." The folk-tale of paupered prince or stolen princess who never, though reared as swineherd or scullion, loses regal bearing and courtly demeanor, the wide respect for royal blood, and the easy belief in the "born criminal," alike testify to the common and venerable persuasion that minds, and even morals, are subject to hereditary transmission.

It is only when we stop to inquire precisely what is inherited in all these instances, and how it is conceivable that mind should pass from parent to offspring, that we leave the highway of common sense and enter the more difficult path of critical observation and induction. It is obvious that a clear statement of the problem and a forecast of method are of the first importance.

Inasmuch as the notion of "inheritance" involves both the process and the products of transmission, the inheriting and the thing inherited, a choice of methods is at once suggested. Shall we—that is to say—seek to describe the mechanism of inheritance, or to discover the like qualities that have actually appeared in successive generations of blood-relatives? It is quite impossible to state the alternatives without adverting to the fact that biology has, for a half-century, been absorbed in the parallel investigation of physical inheritance. Nor are we likely to forget, in the midst of our commemoration of Darwin's birth and of "The Origin of Species," that the whole doctrine of organic evolution rests upon the facts of heredity. Whatever the factors that determine racial descent—fluctuating variation, or the sudden change of type, use and disuse, natural, artificial, sexual or organic selection—both continuity in the process of bionomic change and maintenance of the change once produced, demand the conception of a hereditary likeness. Without inheritance the establishment of a stock would be impossible, and without a stock, variations and mutations


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462 would be chaotic and without significance. Thus, ever since Darwin's own attempt at a theory of heredity, we find the students of organic evolution and the breeders of plant and animal races alike devoting themselves to the problems of racial and individual inheritance.

Now it is plainly futile for the psychologist to pretend to firsthand knowledge in a field which is not his own; but, on the other hand, it is equally foolish for him to proceed to the question of mental inheritance without a conception of the methods used, and of the general progress made, by the biological sciences in like inquiries. He must at least bear in mind that the days of pangenesis were followed by the days when Weismann challenged the Lamarckian doctrine of use and disuse, these by the days of rapid development in cytology (the science of the cell and its development), and these days, in turn, by the establishment of the science of genetics and of a revised, if tentative, doctrine of heredity. He must also keep in view the general march of events that led up to the rediscovery of Mendel, the attempt to establish "unit characters" and to segregate the elementary factors in descent, the exploitation of sudden or discontinuous variation at the expense of fluctuation, and the wide use of Quetelet's discovery that individual variation follows the law of probability.

But what, you may ask, has psychology to learn from the doctrine of physical inheritance, when bionomic orthodoxy is overgrown with speculation, when evolutionists themselves are asking, fifty years after Darwin, whether the time is yet ripe for a discussion of the origin of species, when they are raising the doubt whether there has yet fallen from the tree of knowledge the apple that shall suggest the discovery of the universal law of inheritance; when Strassburger affirms that the doctrine of heredity must rest upon the study of the cell, and Bateson replies that the student of evolution is "still, as a rule, quite unable to connect cytological changes with any genetic sequence," and that the direct examination of parent and offspring, not of the germinating cell, is the present key to the problem? What can the psychologist hope to learn about method when the biometrician and the follower of Mendel stand at sword's points; the one fighting for measurements, and schemes of distribution, and coefficients of correlation, and the other for segregation, unit characters and laws of dominance and recession?

My reply is, first, that, in spite of his keen enjoyment of the battle, even the observer from the outside can appreciate the invention and application of clever and useful methods and the advancement of knowledge through conflict; and, secondly, that the student of mental inheritance must get at least half of his equipment from the antecedent studies of biology. To be sure, he finds his material within psychology; but he sees that the strict dependence of mental upon physical derivation calls for an alliance with both the biometrician and the student of physiological genetics.


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Rh Let us be more concrete in this matter. If I catch the drift of biological discussion (a hazardous assumption, it may be, for the layman in biology to make), no current and generally accepted doctrine of heredity is able to trace in an unbroken series of structures or events the details of the parental organism through the stages of reproduction to the corresponding details of the offspring. The nuclear and nonnuclear substances that are supposed to represent the "vehicle" of heredity do not, I think (except, perhaps, in a few cases) show variations that represent and correspond to the likeness or difference in given characters as these appear in parent and offspring (e. g., differences in height, in shape of leaf, or in color of hair). If, at some future time, these variations are discovered, then they will, I suppose, represent or correspond to mental as well as physical likeness and difference. At present, however, degree of likeness in blood-relations must be derived from description or measurement of corresponding characters or qualities to be observed in succeeding generations. And the point at which we are here aiming is this: the establishment of inheritance of these qualities, whether physical or mental, must, in principle, rest upon one and the same basis. The inheritance of eye-color and the inheritance of memory-type, the inheritance of an "athletic build" and the inheritance of a bad temper are facts of the same order, and similar methods may be laid under prescription for their establishment.

The great difficulty lies here: how are the characters, mental and physical, to be conceived? and how are they to be described and measured?

We have just seen that upon this question of analysis and measurement, quite apart from the problem of mechanism, the schools of evolution show wide differences of opinion, the biometrician basing his method upon the doctrine of probabilities and proceeding quantitatively, the Mendelian basing his method upon the doctrine of unit characters and segregation and proceeding analytically and by distinction of qualities.

Which of these methods, if either, is psychology to adopt? It happens that psychology has already made a provisional choice; or rather, a choice has been made for her. Biometry has been predominantly concerned with human, Mendelism with non-human, inheritance. It is scarcely an accident, then, that biometrical methods were the first to exploit the mind of man. As you know, biometry's inspiration came from Francis Galton, traveler, explorer, geographer, anthropologist, student of evolution, psychology and sociology. The grandson of Erasmus Darwin, a representative therefore of one of the highly gifted strains of English blood, Galton has devoted himself to a quantitative study of the inheritance of talent and intellect, and to practical measures for purifying and improving the race. His interests revolve


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464 about the central theme of human ability and its dependence upon the stock. In a study of three hundred eminent English families, Galton found the descent of great mental capacity to be far more intensive than in less eminent families; and found, further, that the closer the blood-relationship, the greater was the number of eminent individuals. Later studies, for example, Galton's own recent inquiry into the family history of Fellows of the Royal Society, have likewise shown that the person of superior mind is much more likely than the average to possess superior ancestors and descendants. These facts are justly interpreted as an indication that mental endowment depends in large measure upon direct inheritance.

This kind of inquiry then—the kind that takes human beings in the mass and applies a rough unit of measurement—reveals in a striking way the importance of the hereditary factor in mental ability. However, the method does not constitute a science of heredity. No evolutionist would be satisfied to know that large horses beget large horses, and small horses small horses. It is the degree of likeness of some particular organ, or quality, or function, or peculiarity that the student of heredity now attempts to state, and to state often in numerical terms.

So the present psychological problem of heredity comes back to the question of mental characters and of the best methods for their description and measurement. The psychologist may answer this question in either one of two ways. First, he may fall back upon the distinctions of every-day or popular psychology and say that "a good memory," "sound judgment," "conscientiousness," "affability," "sentimentality" and "industry" are mental characters, and that the way to calculate their heritability is to take a large number of persons, related and not related, estimate the eminence of these qualities in each, note their distribution and derive laws of resemblance. If you find that a good memory, or affability, or industry "runs in families," and is not to be attributed to a common environment, you may conclude that the characteristic in question is heritable. As a matter of fact, this is the method that, for the most part, has been employed within the last ten years; and it has been used either by biometricians themselves, or by the psychologist who has followed their initiative.

Let me cite two or three instances. Professor Karl Pearson, of the University of London, the leader of the biometrical school, collected from teachers data regarding some four thousand children. Color of hair and eyes and cephalic index were among the physical characters graded, and conscientiousness, temper and assertiveness among the mental traits. The degree of likeness between brothers and sisters was found to be substantially the same for physical and mental qualities; in Pearson's terms, each showed a correlation of about 0.5. Again,


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Rh Professor Thorndike, of Columbia University, in a study of fifty pairs of twins, by the use of tests and measurements, derived nearly the same degree of correlation (just exceeding.75) for mental and physical characters—a much higher degree of resemblance, by the way, than he found in brothers and sisters not twins. The result is noteworthy, even though we may doubt the full validity of the method. The most extensive and painstaking investigation of this order was recently made by two Dutch psychologists, Heymans and Wiersma, of the University of Groningen. Some four hundred physicians responded to a questionary, each giving the results of his intimate acquaintance with a single family. The questions asked pertained to the ardor, impulsiveness, resolution, persistence, generosity, temperance, wit, patience, industry, etc.—about ninety topics in all—of each member of the family selected. The results when thrown into tabular form indicate a high degree of resemblance between parent and child—a higher resemblance between father and son, mother and daughter, than between father and daughter and mother and son. Even after allowance had been made for cultural influences, the degree of likeness was about the same as the inheritance of bodily stature, and the result seems, moreover, to stand in close agreement with Galton's law of ancestral inheritance, which accords to the average parent one quarter the heritage of the offspring.

It is, now, a matter of interest that these studies and others that might be brought under survey suggest that our mental traits and capabilities are derived, very much as are our bodily characteristics, from hereditary endowment. You must, however, have been struck by the grossness of the method of collecting facts. What is the scientific value, you may have asked yourselves, of a teacher's or physician's opinion that A is more vivacious or less generous than B? Well, the outcome does show, I think, that careful mathematical treatment of extensive data thus collected will yield noteworthy and valuable results. But the more important the results, the greater the demand for refinement of method. Can the method be improved? I think that it can. The biometrician having shown that the problem is capable of solution, let us see if his arch-enemy, the follower of Mendel, can not suggest the improvement in procedure. The improvement that I find suggested is this: the exclusive inheritance of Mendel lays emphasis upon the analysis and separate treatment of individual characters. Now without presuming to decide whether inheritance takes place in all cases, or even as a rule, through the recombination of "unit characters," mental or physical, psychology may profit by the Mendelian* principles so far as to insist that inheritance be studied, not in the; gross, but in terms of definite and measurable mental structures and functions.


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466 This insistence involves the substitution of a doctrine of mental characters for the popular conception of vague and indefinite traits and peculiarities. How is this doctrine to be derived? Obviously from psychology itself. Neither biometry nor biology nor common sense can furnish the materials.

Look with me for a moment, if you will, to see what psychology has to offer. It is evident that the general psychology of the average normal mind will not suffice when the matter is one of defining differences among minds of the same class. Just as physical inheritance must take account of arrays and schemes of distribution, and not of averages, so must mental qualities and magnitudes be arranged with respect to definite individual variations within the class.

A psychology of individual differences is thus invoked; and a psychology of individual differences does exist; or rather, it is in process. The way of scientific description is first to reveal uniformities hidden in the mass, and afterward to seek the rule of variation from the average. General psychology, taken in this sense, is accordingly the older branch of the science—the psychology of what is common to all minds—individual psychology, the newer. So it happens that although the older branch of the science has a well-developed metrical technique, established at almost the same moment that "The Origin of Species" appeared, its quantitative determinations are determinations of psychophysical constants and not laws of individual variation. These laws can not then be used (at least not directly) for the statistical study of inheritance. What is needed is a psychology of typical differences, and this it is that individual psychology is by way of supplying. Let me, in a word, indicate its method. It proceeds by experiment to take the dimensions of mind as regards variable functions, e. g., the maximal amount read in a given time and under given conditions, or the number of words remembered or of figures added. The first results show typical differences as between mind and mind. The experimenter next proceeds to factor the performance into elementary processes and functions. By drawing his conditions closer and closer he discovers that the capacity for reading depends upon such simple factors as the range of consciousness, the degree of attention, and the temporal rate of visual processes, factors all capable of measurement and exact description. He discovers that remembrance depends upon the employment of visual or auditory or kinesthetic processes, i. e., that in one observer an eye-mind, in another an ear-mind and in a third a muscle-mind is employed. Of these factors, he can predicate heritability. It is as if "criminality" were reduced to a lack of motor control plus an abnormally intensive passion or lust. "Criminality" would then never be inherited, but the constituent factors might very well be. The method of individual psychology, however, goes farther. After