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6 SCIENCE-ADVERTISEMENTS VOL. 96, NO. 2486

SCIENCEVOL. 96 FRIDAY, AUGUST 21, 1942 No. 2486

American Geology, 1850-1900: DR. BAILEY WILLIS ... 167 Special Articles:

Physics in Industry: DR. E. U. CONDON................................. 172 The Growth-Stimulating Effect of Biotin for theDiphtheria Bacillus in the Absence of Pimelic

Scientific Events: Acid: PROFESSOR VINCENT DU VIGNEAUD ANDOTHERS. A Biosynthesis of Biotin: DR. ROBERT

Recent Deaths; The Nutrition Foundation; The E. EAKIN and ESTHER A. EAKIN. Tetraploidy inIndustrial Nutrition Advisory Service; The Na- Antirrhinum Majus Induced by Sanguinarine Hy-tional Roster of Scientific and Professional Per- drochloride: THOMAS M. LITTLE ............... ........... 186sonnel; The Buffalo Meeting of the AmericanChemIca Society.174 Scientific Apparatus and Laboratory M~ethods:em itcal Society .......................................... 17

Bacterial Activity in Dilute Nutrient Solutions:Scientific Notes and News . . . . . 177 DR. CLAUDE E. ZOBELL and DR. CARROLL W. GRANT.

Preserving Plant Viruses in vitro by Means of aDiscussion: Simplified Lyophile Apparatus: T. P. DYKSTRA

The Blood Pressure in the Umbilical Vein of the and DR. H. G. DU Buy ................... 189Foetal Sheep: SIR JOSEPH BARCROFT AND OTHERS. Science News ................... 8Fusion of Top Soil by an Electric Arc: DR. KARLVER STEEG. Modern Facsimile Reproductions ofRare Technical Publications: DR. E. D. MERRILL 179

* ~~~~SCIENCE: A Weekly Journal devoted to the Advance-Quotations: ment of Science, edited by J. MCKEEN CATTELL and pub-

Artificial Antibodies ... 181 lished every Friday byTHE SCIENCE PRESS

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The Pennsylvania Committee for the Promotion of ing membership in the Association may be secured fromScience in Secondary Education . 185 the office ofte e pepermanent secretar In the Smithsonianciene in econd ry Ed catio ...................................InstitutionsBuildingi Washingtong D., C.

AMERICAN GEOLOGY, 1850-19001

By Dr. BAILEY WILLIS

STANFORD UNMIITY

IN 1850 the knowledge of geology was in an earlyexploratory stage, especially in America. In Englandand Europe sufficient progress had been made in thestudy of the stratified rocks and their contained fossilsto contrast markedly with American lack of observa-tions. It could not have been otherwise. The firsttask of a geologist, entering upon a new field, is todiscover and locate the various rock formations. Hemust have a map, upon which to delineate their distri-bution. But in 1850 the mapping of America wasvery crude. Even the eastern country was knownonly in broad outline and the -west was imperfectlyexplored. Nevertheless, by 1850, material progress

1 Abstract of address before the American PhilosophicalSociety, February, 1942.

had been made in determining the ages and distribu-tion of the sedimentary rocks of the United Stateseast of the Mississippi and of Canada. Logan ofCanada, Hall of New York, the Rogers brothers ofPennsylvania and Virginia, Safford of Tennessee,and many others who felt the urge to read the recordin the rocks, had identified the strata of certain greatperiods of geological time, had classified them in orderof relative age, and had mapped them with suchaccuracy as the conditions permitted.

That they had been able to accomplish so much wasin part due to the fact that the great leaders in Englishgeology, Sedgewick and Murchison, had establishedfor that country a succession of strata and fossils,which is the same as that of eastern North America.