characteristic phenomena, describe them particularly, noticing the individual details, and endeavor to make the one case thoroughly understood in all its important relations, so that it becomes the illustration of the several principles involved. Thus, in explaining volcanoes, instead of spending the time with an enumeration of statistics and formulæ, crowding the lecture with all the information possible about volcanoes, the whole lecture may be spent upon Vesuvius, its environs and history, making vivid impression of one or two typical eruptions, and, by the aid of maps of the region, pointing out the precise phenomena in the locality, sequence and results in building a cone and making volcanic deposits. With a clear notion of one such typical volcano, it is a simple matter to classify and point out the kinds of volcanoes, the pure tufa eruption, as at Monte Nuova, the continuous lava flow, as in the Sandwich Islands, and by means of the grand eruptions recorded of Skaptar Jokul, to gain a conception of fissure eruptions and the nature of the vast lava-fields covering now such large tracts of the surface, but without the conical mountain peaks which we naturally associate with igneous eruptions. In the same way in treating of river dynamics, instead of brief descriptions of the great rivers of the globe, the amount of their erosion and sedimentation, the volume and rate of their waterflow, etc., presenting a great number of condensed statistics about many rivers, a better way is to spend the time in explaining the facts and their interrelations for a single typical river. No better example can be found for us than our great river Mississippi, so thoroughly studied and reported upon in Humphrey and Abbott's monograph. For illustration of the principles of erosion a familiar ravine, near by, is better than a large rivergorge at a distance. Niagara may well serve to illustrate the rate of erosion and as a short measure of geologic time. The cañons of the plateau district are illustrative of the laws of continuous depositions, of slow but great elevation, and furnish a longer but conceivable measure of time for geologic events. So in all cases, where it is possible, selection should be made of a familiar and typical example, and around it should be gathered the details of facts and phenomena which will illustrate the principles discussed. By communicating a clear, detailed conception of the one example, the indistinctness and often bewilderment arising from the array of a multitude of statistics in regard to many examples is avoided. At first sight this method may appear like a mere popularizing of a science, and-the aspect which might be so called,— the attempt to make comprehensible and therefore interesting, what is generally not so, is worth seeking after. Is it not this very element of exciting interest, of pleasing the hearers or readers, that made the writings of Lyell and the lectures of Louis Agassiz so attractive and also so instructive? The boys in college learn the principles of geology in the same way that we learn new laws and principles in our deeper investigations. It is facts and phenomena first, afterwards their interpretation; and unless they gain a vivid impression of the former, they will come short of grasping the latter. The other method of memorizing the statements of the laws and principles of the science, without any clear conception of the facts to which they apply, is only a knowledge of words; it is not science; and such knowledge has no scientific value. In field and laboratory work the main point is to teach the student to observe, to record, and properly to interpret facts as they occur in nature. This is not accomplished by simply walking over the ground and pointing out the phenomena to the class. In one way and another they must be led to see for themselves; they must gather the facts, study and arrange them. The teacher may show them how to make sections, and how to gather facts and specimens. Section after section may be made through similar series; geographical localities, altitude, thickness, dip, lithological character, and fossils should be observed, and notes and materials brought in for study. After numerous sections are thus in hand, my plan is to call for a report upon the region or formations examined, asking for detailed answers to the questions, What are the faunas? What are the differences in the several sections? What changes are seen in the nature of the deposits on passing upwards? What are the names and characters of the individual species? etc. If the student wishes to perfect himself in palæontology, I set him at work on the local palæontology and stratigraphy, causing him to make comparison of sections, of association of species and individual variations, as well as drilling him in the identifying of genera and species; using the local facts, because I find better results from the deep and exhaustive study of what is at hand and is capable of such exhaustive treatment than is possible by the method of discursive rambling over a greater number of facts. The materials ready at hand for us at Cornell University are Devonian; but the student who has learned accurately to identify species of a Devonian fauna has learned the relative importance of characters for classification; has learned the nature of variability, the relation of species to geological horizon, the modification of specific types with retention of generic features on passing from zone to zone; has studied the range and distribution of the species; has gained a conception of what faunal association is and how it is related to the lithological character of the deposits; I say the man who has grasped these details of the science by the use of Devonian material alone is ready to undertake investigations in any geological period, from the Cambrian to the Tertiary. The facts may differ, but the methods of research will be the same; and this method and skill cannot be attained by any amount of the mere memorizing of the names of a labelled collection of fossils. It is a mistaken view to imagine that that kind of acquirement which only removes the Megatherium, the Ichthyosaurus, the Trilobite, and the Palæoniscus from the region of wonderland to a place among the things we have seen, is geology. So long as we use our museums as curiosity-shops and cover our ignorance with Latin nomenclature, we cannot expect to lift our science out of the region of crudities. There is, however, some value to be derived from studying over labelled collections, but this must not be without the study of the fossils as they occur in the rocks, and the determining of the characters, the names, and the horizon, each man for himself. And if the rocks are crystalline and not fossiliferous, this determines beforehand that there are not present the best facilities for the study of paleontology, although great museums may have been accumulated. The natural rock foundations of the region in which a university is built thus decide the particular part of geological science which may be there taught most successfully. To this fact may be traced the explanation why Harvard, Yale, and Amherst have been so prolific in physical geologists and mineralogists; why New York State has given us so many palæ ontologists; why the geologists of Pennsylvania have taught us so much about stratigraphy and the structure and products below the surface. In each institution the natural advantages found in the accessible rock exposures of the region should be not only carefully studied, but should be made a prominent feature in all the advanced work of the college. In conclusion, I would remark that (a) the fundamental nature of the subject-matter of geology, with its many still unsolved problems, its many mysteries, its many unique and wonderful facts, will tempt the instructor to deal with generalities, to rest satisfied with a superficial rather than a scientific presentation of his subject. As a means of escaping this danger I suggest a careful attention to the natural order of the acquisition of the facts, a following of the analytical order, from the conspicuous, the evident, the general, to the special, the hidden, the individual, or, to use another form of expression, follow the order of induction from the concrete, the typical, the illustrative, to the principles involved to the formulation of the laws of nature. (6) Further, I would suggest the great value of selecting a single typical illustration of each general principle, presenting it with considerable attention to details, pointing out its specific characteristics. This example, then, may be adopted as a standard for comparison with other cases which offer modification of the laws. involved in the first typical case. (c) In field and laboratory work the same method may be applied with good results. In this part of the study problems which are accessible, in which the student can investigate the details and gather numerous statistics mutually bearing upon each other, are to be selected. In this way the region in which he studies becomes one of the chief factors in developing his powers of investigation and in showing him how to interpret nature. He thus studies nature from the original text, instead of reading merely the translations made by others. (d) In all the various departments of the science I would seek to teach the student precision and definiteness in his knowledge, and accuracy in his modes of thought, by applying the simple rule of teaching much about a few things, instead of attempting to say a little about a great many things. THE RANGE OF VARIATION OF THE HUMAN SHOULDER-BLADE. THE BY THOMAS DWIGHT, M.D.' HE late Professor Broca read a paper before La Société d'Anthropologie in 18782 in which he described the scapular and the infra-spinous indices, and proposed them as methods of ethnological research. Briefly stated, the scapular index is the proportion of the breadth of the scapula, measured along the base of the spine, to the length, the latter being considered one hundred. The infra-spinous index is the proportion of the breadth to the length of the infra-spinous fossa, the latter being considered one hundred. CD The human scapula being the starting-point, Broca understands by "length" the line connecting the highest and lowest points, although in almost all mammals this is not the longest dimension. The line showing the breadth being called AB and that of the length CD, the index is obtained by calculating 100 X AB The length very rarely coincides with the posterior border of the scapula, but runs some distance before it. The line AD representing the infra-spinous length runs from the posterior end of AB to the lower end of CD. spinous index is represented3 by the fraction Broca used these indices both in comparative anatomy and in the study of characteristics of race, sex, and age in man. 100 X AB The infra Professor In all orders of mammals, with one exception, the scapular index is greater than in man. In quadrupeds it is evident that the long diameter of the bone should at least approximately coincide with the line of pressure, and consequently we find the breadth-i.e, the line along the base of the spine-the longer. In erect man, with his great range of movement of the anterior extremities, there is need of greater leverage for the movements of the scapula, and less need of resistance to pressure, so we find a long and narrow scapula. This condition is approached in the anthropoid apes, and even surpassed in the bats, who have a Parkman Professor of Anatomy at Harvard University. 2 Bulletins de la Société d'Anthropologie de Paris, série 3, tome i. 3 By a most unfortunate oversight the AB and AD are transposed in Broca's paper. |