in at least physiology, biochemistry and bacteriology. Anatomy is required at Hopkins and Harvard and the latter school also requires introductory pathology. It is evident that we are approaching the curriculum recently advocated by Sedgwick (5), who advised identical training for medicine and public health students for two years with divergent paths for two years more. Public health further requires somewhat more elaborate training of its students in certain branches of zoology, notably in parasitology, protozoology, helminthology and entomology, than is usually required of medical students.

Then come the medical and pre-medical sciences specifically applied to public health problems. Advanced physiology particularly of fatigue, respiration, climatology and ventilation; chemistry as applied to nutrition and metabolism, food, food adulteration and sanitation; bacteriology as applied in public health laboratories and to sanitary engineering.

And lastly are the public health sciences properly speaking: vital statistics, public health administration, sanitary law, sanitary engineering, epidemiology, school inspection, control of contagious diseases, and the like. The total curriculum is certainly medical enough in aspect, which accounts for the very natural supposition in the minds of the general public and of many of the medical profession that public health is simply another specialty of medicine. How far wrong this conception is I shall hope to bring out a little later. Let it suffice here to note that the medical bulk of public health as outlined in schools of public health is preventive medicine and not curative medicine, medical science and not medical art. This is clearly brought out by the almost complete absence in all these curricula of the medical clinic. The hospital is not a necessary adjunct in public health training.

In finally considering the scope of public health we may glance at it as mirrored in current textbooks. Here at least no practical consideration of money or men need limit the field to be covered. Again the main emphasis

1 Rosenau (6), Park (7), and Abel (8) were consulted in this connection.

very properly lies in disease prevention with rather more emphasis than in the course outlines on certain correlated branches of personal hygiene and community welfare; the construction of dwellings; the question of clothing; the group care of infants and school children; health measures as applied to prisons, to armies, to transportation, and the tropics. A wider field is suggested by mention at least of such deeply specialized fields as mental hygiene (Park) and eugenics (Rosenau).

It is evident then from these summaries that public health is primarily concerned and properly so with the abolition of disease and in this campaign has enlisted the cooperation of many specialists outside the field of medicine. We suggest again that its future lies in the further assumption of the burden of combating ignorance, vice, crime, and poverty. What then is the actual and prospective personnel of the army of public health workers? Since disease is and will probably remain its most serious, tangible and defeatable enemy the man with a medical training is the most considerable figure in the scheme. Undoubtedly a full medical training remains the best foundation on which to base a further training in the broader field of public health. As an entire training medicine alone is inadequate, and to the type of mind that remains satisfied with accomplishment of the diagnosis and cure of an individual case of disease, it may even be detrimental. This is no place for the guild-consciousness of the practitioner of medicine. As a matter of fact the graduate in medicine is no longer of necessity the forwarder of those very sciences on which the art of medicine depends. If it be true that physiology, bacteriology, biochemistry and anatomy are progressing in the hands of non-medical specialists to the ultimate advantage of medical practise, this is even more true of the field of public health. No one would dream of asserting that one must have a medical training to be a good sanitary engineer, social worker, or criminologist. In this connection it is of interest to note that less than half the faculties of

the Yale and of the John Hopkins Schools of Public Health are doctors of medicine.

May I point out then in conclusion that there are a number of fields of human endeavor that have been largely or entirely overlooked in efforts to present the scope of public health? They overlap each other and the fields already recognized.

The whole field of social economics has been notably neglected. The study of poverty, care of dependents, the question of housing from the standpoint of the inhabitant; some conception of city government, and the labor problem may be mentioned as contributory in this training.

Further consideration of industrial hygiene is necessary not simply from the standpoint of occupational diseases and accident prevention but from the aspect of labor education and efficiency.

There is a group of studies that may be included under mental hygiene: psychology; abnormal psychology; criminology, the studies of vice, and delinquency. Closely related thereto are the endeavors in child hygiene and child welfare, eugenics, juvenile court work and the like.

Somewhere in the scheme I am sure should come certain aspects of physical education as a building method of the healthy mind and body. And perhaps, as Vincent has suggested, we should consider some forms at least of proper publicity and education of the masses in the results of public health work.

The whole business of public health action then seems dependent on those who have specialized information in any one of the numerous branches that have and will comprise it. The further development of this art depends on those with successively larger visions of what's wrong with the world.

BIBLIOGRAPHY

1. Southard, E. E. The Kingdom of Evil: Advantages of an Orderly Approach in Social Case Analyses. Proc. Nat. Conf. of Social Work. Pamphlet No. 179, 1918.

2. Vincent, G. E. Public Health Training in Universities. Jour. A. M. A., 1917, 68, p. 1013.

3. Winslow, C.-E. A. The Untilled Fields of Public Health. SCIENCE, 1920, 51, p. 23.

4. Ferrell, J. A. Careers in Public Health Service. Jour. A. M. A., 1921, 76, p. 489. Modern Medicine and the 5. Sedgwick, W. T. Public Health. Public Health Reports, 1921, 36, p. 109.

6. Rosenau, M. J. Preventive Medicine and Hy giene. Appleton & Co., 1913.

7. Park, W. H. Public Health and Hygiene. Lea and Febiger, 1921.

8. Abel, R. Handbuch der Praktischen Hygiene. Fischer, 1913.

FREDERICK P. GAY

UNIVERSITY OF CALIFORNIA

THE ABORIGINAL POPULATION OF

CALIFORNIA'

THE only attempt to compute the aboriginal population of California is that of C. Hart Merriam in the American Anthropologist for 1905. His figure of 260,000 was obtained thus: In 1834 there were 30,000 converted Indians at the Missions. The addition of unconverted Indians within the Mission area would make 40,000. The population at the Missions had suffered a decline; correct therefore to 50,000 for aboriginal times. The Missionized area embraced one fifth of the habitable area of the state. The total would be 250,000; to which add 10,000 in the mountains and deserts.

This computation appears to err on the side of the area tapped by the Missions, which should be estimated at one third rather than one fifth of the total, reducing the result to 150,000 or 160,000.

Calculations gradually made during the past twenty years suggest a still lower figure, 133,000. This is the aggregate of the closest possible estimates which can be made for individual tribes and groups. For instance, a close survey of the Yurok shows them inhabiting between 50 and 55 settlements at the time of discovery. The houses averaged 6 per settlement, the inmates 7.5 per house. The total of approximately 2,500 for the Yurok, together with less complete data on number

1 Abstract of a paper presented before the Section of Anthropology, American Association for the Advancement of Science, Chicago.

of settlements among neighboring tribes and valuations of their territory as to food supply, allows figures to be set for these other tribes. The figures for the entire district can then be used as a check on estimates made independently from local sources for other districts, due regard being given to variety of geographic conditions. In this way the total is arrived at.

The best early data are those from Spanish sources, which sometimes include approximate counts. Early American figures are usually impressionistic and exaggerated.

A check is furnished by the large Yokuts group. Here Moraga in 1806 computed 3,760 souls in thirteen tribelets, an average of 290. The inclusion of absentees might bring the figure to 350. Nearly 50 such tribes are known among the Yokuts, with a small part of their area unaccounted for. The total population of the stock thus was about 18,000. Its area embraced about one ninth of modern California and seems about average in food-supplying capacity. Multiplying 18,000 by 9 gives 162,000. A deduction of one fifth for the larger blocks of high mountain and desert areas brings the total to about 130,000; a reasonable verification.

Of course, no figure can be more than an approximation; but it seems at least highly probable that the native population fell between 120,000 and 150,000.

Even this total, the lowest ever arrived at, yields the unusual density of nearly one inhabitant per square mile for aboriginal California. Mooney's estimate is about 1,050,000 for the continent north of the Mexican boundary; 846,000 within the limits of the United States exclusive of Alaska.

The latter figure however, seems to contain Merriam's 260,000 for California. Reduced to conform to the new estimate of 133,000, the population of the United States would not much have exceeded 700,000, or one inhabitant per four square miles. In other words, more than a sixth of the Indians of this country were settled in California. A similarly heavy concentration seems to have held good for the

THE CENTENARY OF THE BIRTH OF HERMANN VON HELMHOLTZ SCIENTIFIC men of the twentieth century are so engrossed in their various pursuits (for which, happily, material equipment far in excess of anything dreamed of fifty years ago is provided) that they are in some danger of forgetting, overlooking or even ignoring the work of their predecessors of the nineteenth century.

It is upon fundamental discoveries in electricity and magnetism made during that century, and especially upon the two great generalizations, the law of the conservation of energy and the doctrine of evolution, which together constitute its great glory, that the present generation is building a brilliant, though a somewhat complicated and bizarre superstructure. It may be well, therefore, to remind the group of busy younger men who read the pages of SCIENCE, that one hundred years ago, August 31, 1821, was born one who must always be ranked with the very first-the three or four very first-of those upon whose work twentieth century science rests.

Hermann Ludwig Ferdinand, Baron von Helmholtz, was the son of a professor of philology and philosophy at Potsdam. His mother was a Hanoverian lady, a direct descendant of William Penn.

Exhibiting at an early age a fondness for the study of natural phenomena, the necessity for a vocation by which he could earn a living directed him to the medical profession and his first appointment was as an army surgeon.

At the age of twenty-one years he published his first paper announcing the discovery of nerve cells in ganglia, the beginning of a steady flow of contributions to science from his pen, interrupted only by his death more than fifty years later.

At twenty-six he had produced what was possibly the most important piece of work of his whole career, namely, his famous paper on the conservation of energy. Refused for publication by Poggendorff's Annalen, its value was appreciated by Du Bois-Reymond, who presented a copy of it to Tyndall (then a student at Berlin) with the remark that it was "the product of the first head in Europe." This paper fixed his place as one of that immortal trinity, Joule, Helmholtz and Kelvin, to whom we owe the establishment of this great law.

An account of Helmholtz's principal contributions to science was given in this journal not long after his death, together with the leading incidents of his long career.3

In one respect he was unique. No other man of his day approached him in the wide range of his intellectual activities, ranking, as he did, among the first of mathematicians, physicists, and physiologists, besides being claimed as "their own" by chemists and musicians. His contributions to the science of astronomy and of theoretical mechanics are of the highest order and in respect to his prodigious learning and the wide scope of his investigations he may be put in the same category with Francis Bacon and his own renowned fellow countryman, Alexander von Humboldt. The enormous extension of the bounds of human knowledge within the past fifty years and the irresistible tendency to specialization make it certain that there will never be an addition to

There was a certain massiveness of style in both his speech and composition which made his arguments a little more difficult to follow than was the case with his two or three more brilliant contemporaries. The charm of his personality will not be forgotten by those who had the good fortune to come within its sphere. With much dignity of manner he was easy of approach, simple and modest in his mode of life, eloquent in speech in popular addresses on scientific subjects, and to those who had tried to find the man in his published works, unexpectedly delightful in social inter

course.

Physically he was not above the average in height and in figure much like that of the well-bred and well-fed German. The one small disappointment was his head which, though large, did not in shape at once proclaim his intellectual superiority, as did that of von Humboldt.

Personally chosen by the Kaiser to represent the German Empire, he came to the United States at the time of the World's Fair in Chicago in 1893. He was honorary president of the International Electrical Congress, with its "Chamber of Delegates" assembled at that time and through the kindness of friends, official and unofficial, all of whom were glad to do him honor, he was enabled to see the places and things most worth seeing in this country which he had never before visited.

On the voyage back to Germany he met with an accident which resulted finally in his death in September, 1894, mourned, as he had been beloved, by people of every nationality and all ranks of life.

The then youthful Kaiser, who was very fond of von Helmholtz and who two years earlier on the occasion of his seventieth birthday, had placed him at the head of the civil list, judged wisely in selecting him as the "highest product of the Empire" and in pure intellectual power he will always rank with the foremost men of the nineteenth century.

RAVENNA, OHIO

T. C. MENDENHALL

Schwalbe, Strassburg, on April 23, 1916, age seventy-one years; and Professor Karl von Bardeleben, editor of the Anatomischer Anzeiger, on December 19, 1918, age sixty-nine

SCIENTIFIC EVENTS / DEATHS OF GERMAN MEN OF SCIENCE 1

Ar our request, Professor C. Runge, of Göttingen, has been good enough to send us the following list of leading men of science in Germany who have died since the beginning of the late war. The list is not, however, complete, and may be supplemented later. Short obituary notices of some of the men will be found in the Geschäftliche Mitteilungen der Göttinger Gesellschaft der Wissenschaften, 1918-19-20 (Weidmannsche Buchhandlung, Berlin S.W. 68, Zimmerstr. 94):-W. Lexis, mathematician and statistician, August, 1914; W. Hittorf, physicist, November, 1914; A. von Auwers, astronomer, January, 1915; A. von Könen, geologist, May, 1915; E. Riecke, physicist, June, 1915; P. Ehrlich, physician, August, 1915; H. Solms-Laubach, botanist, November, 1915; R. Dedekind, mathematician, February, 1916; E. Mach, philosopher and physicist, February, 1916; K. Schwarzschild, astronomer, May, 1916; R. Helmert, mathematician and physicist, June, 1917; A. von Baeyer, chemist, August, 1917; G. Frobenius, mathematician, August, 1917; A. von Froriep, anatomist, October, 1917; H. Vöchting, botanist, November, 1917; C. Rabl, anatomist, December, 1917; G. Cantor, mathematician, January, 1918; L. Edinger, physician, January, 1918; E. Hering, physiologist, January, 1918; F. Merkel, anatomist, May, 1919; S. Schwendener, botanist, June, 1919; E. Fischer, chemist, July, 1919; H. Bruns, astronomer, 1919; Th. Reye, mathematician, July, 1919; W. Voigt, physicist, December, 1919; P. Stäckel, mathematician, December, 1919; W. Pfeffer, botanist, January, 1920; O. Bütschli, zoologist, February, 1920; and W. Förster, astronomer, 1920. J. Elster, physicist, and Joh. Thomae, mathematician, have died recently. In addition to the above, several other German men of science were referred to in the obituary notice of Professor von Waldeyer in Nature of May 19, and news has also reached us of the following deaths not previously recorded in these columns:-Professor G. A. 1 From Nature.

years.

PROGRESS IN THE WORK OF MAPPING THE UNITED STATES

THE United States Geological Survey, Department of the Interior, has published about 3,000 engraved topographic maps, which represent nearly 43 per cent. of the area of the United States. These maps are the results of surveys made during a period of 34 years, and the results are fairly good in quantity and quality for a Government bureau which can go only as fast as appropriations will permit.

A few geologic maps were published by the Survey prior to 1886, some of them in atlases accompanying reports on regions in the West, and a few were published separately as photolithographs; but the 1-degree sheets of northwest New Mexico and northeast

Arizona, known as Wingate and Mount Taylor, N. Mex., and Fort Defiance, Tusayan, Marsh Pass, and Canyon de Chelly, Ariz., published in 1886, were the first topographic maps printed by the Geological Survey from engraved plates.

Eight States-Massachusetts, Rhode Island, Connecticut, New Jersey, Delaware, Maryland, West Virginia, and Ohio-have been completely mapped, and the work of mapping the State of New York is more than 90 per cent. completed. Several States are actively cooperating with the Survey in this work and in 1920 contributed to it a total of nearly $200,000.

The Bulletin of the Survey containing this information continues:

With nearly 60 per cent. of the area of the country entirely unmapped and much that has been mapped in need of resurveys, and with the largest mapping organization in the country surveying only about 40 per cent. of the area in 40 years, the logical demand is for more speed. If these maps are to serve their full purpose in promoting national development the whole country must be mapped within this generation, or, even