We have been handling Natural History Material of all kinds for the past fifty years, and so have accumulated a very complete stock. Our prices are as low as the quality of the specimens will permit. We are constantly preparing circulars and price lists covering our different material in the branches, which we will be pleased to send free of charge to the readers of Science. Some of our recent circulars: S-121 Rare Bird Skins CONCHOLOGY GEOLOGY Georgetown University SCHOOL OF MEDICINE AND DENTAL DEPARTMENT The Sixty-fourth Session began in September and con tinues eight and one-half months. Six-Year Collegiate and Medical Course leading to degrees B.S. and M.D. Practical laboratory work under special instructors, in Anatomy, Physiology, Chem. istry, Histology, Pathology and Bacteriology. Ample facilities for clinical experience and practical work in hospitals of city and in the University Hospital, containing in all over 3,000 beds. For particulars address GEORGE M. KOBER, M. D. Washington, D. C. Marine Biological Laboratory 1. WOODS HOLE, MASS. Biological Material ZOOLOGY. Preserved material of all types of animals for: class work and for the museum. 2. EMBRYOLOGY. Stages of some invertebrates, fishes (in. cludir, Acanthias, Amia and Lepidosteus), Amphibia, and some mammals. 3. BOTANY. Preserved material of Algae, Fungi, Liverworts, Mosses, Ferns and Seed Plants. 4. MICROSCOPE SLIDES in Bacteriology, Botany and Zoology.. 5. LIFE HISTORIES, Germination Studies, and Natural His tory Groups. Catalogues furnished on application to GEORGE M. GRAY, Curator Woods Hole, Mass. BAUSCH & LOMB OPTICAL CO. 550 St. Paul Street, finders and Gun Sights for Army and Navy, Search- that eyes may see better and farther. STUDENTS' MICROSCOPES The "Praxis" Stand is the Student's model pa excellence. Made throughout with the same a curacy and finis as on Watson highest price Stands. A few special poin are:- Standardiz tion so that add tional movemen may be fitted as r quired. Lever fi adjustment. Co structed of tw /solid castings a indestructible. parts are slotted a sprung to compe sate for wear. Catalogue of Microscopes and accessories f W. WATSON & SONS, Ltd. 313, High Holborn, London, England Naturalists' Supplies We carry stock for prompt delivery I. Collecting Utensils. II. Breeding Apparatus and Cages for Living Animals. K-S Museum Cabinets of Glass and Metal New Illustrated Biological Catalog will be sent free of charge upon application THE KNY-SCHEERER CORPORATION Department of Natural Science G. Lagai, Ph.D. 404-410 WEST 27TH STREET. NEW YORK CITY, N. Y. HAR LIBRARY THE SCIENTIFIC MONTHLY SEPTEMBER, 1922 THE REASONABLENESS OF SCIENCE1 ONCE By Professor W. M. DAVIS HARVARD UNIVERSITY A FABLE OF THE TIDES NCE upon a time-for science also has its fables-there dwelt a hermit on the shore of the ocean, where he observed the tides. He measured the period and the range of their rise and fall and, patiently tabulating his records, discovered that the tides run like clock-work. The interval between two high tides was determined to be about 12 hours and 26 minutes; the range from low water to high water was found to vary systematically, being greater one week and smaller the next, the total variation running its course in 14 days; more singular still, the high tides. were found to exhibit an alternating inequality, such that, if they were numbered in order, the even-numbered would be stronger than the odd-numbered for two weeks and then the odd-numbered would be stronger than the even-numbered for two weeks; this cycle of alternating inequality completing itself in 28 days. The hermit then wishing to extend his observations, decided to travel overland to another ocean and learn whether the tides behaved in the same way there also. Now at the same epoch, but far away in the center of a great continental desert, a recluse lived in a cave, thinking and reflecting. One problem in particular engrossed his thoughts. He knew Newton's law of gravitation, and he asked himself what other consequences ought to follow from it besides the revolution of the planets around the sun and of the moons around their planets. He at last convinced himself that if the earth and the moon attract each other, the moon must produce a system of what he called earthdeforming forces, disposed in such a way as to strain the earth's 1 Oration delivered at the annual meeting of the Harvard Chapter of Phi Beta Kappa, in Cambridge, Mass., June 19, 1922. VOL. XV.-13. |