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ELEMENTS OiF GEOPIYSICS. Dr. Richard Ambronn.Translated from the German by Margaret C.

Cobb. pp. xi+ 372. $5.00.

A translation of Dr. Ambronn's book, presenting a gen-eral explanation of geophysical methods to meet the needof geologists and engineers.

DESTRUCTIVE AND USEFUL INSECTS. C. L. Metcalf andW. P. Flint. pp. xii + 918. 561 figures. $7.50.

This book is intended as a text for the beginning studentIn entomology tand also as a guide or reference book forpractical farmers, gardeners, fruit growers, farm advisers,physicians and general readers who desire up-to-date andreliable information about the many kinds of insect pests.

The Macmillan Company, New York

EXPERIMENTAL PHYSICS. Albert E. Caswell. pp. ix +181.

Though this manual may be used in any course in gen-eral physics, it is intended especially to accompany theauthor's text-book " An Outline of Physics." Very little inthe way of special apparatus is called for.

Harper & Brothers, New York

COLLEGE ALGEBRA. N. J. Lennes, with the editorialcooperation of H. E. Slaught. pp. xiv + 301.$2.25.

A special feature of this book is its flexibility. It can beused equally by teachers who desire to make their own in-novations in presenting the subject and by teachers whowish to adhere strictly to the text. A sketch of the historyof algebra Is included.

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National Research Fellowshipsin the Biological SciencesNational Research Council

Post-doctorate fellowships in the Bio-logical Sciences (Zoology, Botany, An-thropology, and Psychology) will beassigned by the Board of National Re-search Fellowships in the BiologicalSciences for the academic year 1928-29 attwo meetings of the Board, one to be heldon February 8 and 3 and the other aboutApril 25th. Applications should be filedbefore January 1st and April 1st, respec-tively, in order to insure consideration atthe following meeting. Appointments maybe made prior to the conferring of the doc-tor's degree, to be effective upon the receiptof the degree within six months. Forms ofapplication and statement of conditionswill be furnished on application by letterfir by wire to

2Uhe Secretary, Board of National ResearchFellowships in the Biological Sciences, NationalReseqrch Council, Washington, D. C.

JAGABI RHEOSTATSmeet a definite need in Educational, Researchand Industrial Laboratories.By means of sliding- We find greatest de-contacts the resistance mand for Rheostatsvalues can be varied with tubes 16" long, asfrom zero to full rat- illustrated above.ing, in exceedingly Write for Descriptivesmall steps. Catalog 1140-S.

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Marine Biological LaboratoryWoods Hole, Mass.

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THIS study represents an experimentalattempt to determine what mental

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STANFORD UNIVERSITY PRESSStanford University, California

WALKER PRIZES IN NATURAL HISTORYTwo prizes, founded by the late Dr. William Johnson Walker, are annually offered by the BOSTON

SOCIETY OF NATURAL HISTORY for the best memoirs written in the English language, on subjects pro-posed by the Board of Trustees.

For the best memoir presented a prize of sixty dollars may be awarded; if, however, the memoirbe one of marked merit, the amount may be increased to one hundred dollars, at the discretion of theWalker Prize Committee.

For the next best memoir a prize not exceeding fifty dollars may be awarded.Prizes will not be awarded unless the memoirs presented are of adequate merit.The competition for these prizes is not restricted, but is open to all. It is nevertheless the tra-

dition of the Society that the founder of these prizes intended them more in the nature of encour-agement to younger naturalists than as rewards for the work of mature investigators.

Attention is especially called to the following points:1. In all cases the memoirs are to be based on a considerable body of original and unpublished

work, accompanied by a general review of the literature of the subject.2. Anything in the memoir which shall furnish proof of the identity of the author shall be con-

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superscribed with a motto corresponding to one borne by the manuscript, and must be in the hands ofthe Secretary on or before March 1 of the year for which the prize is offered.

5. The Society assumes no responsibility for publication of manuscripts submitted, and publicationshould not be made before the Annual Meeting of the Soeiety in May.

SUBJECT FOR 1929: SUBJECT FOR 1930:Any subject in the field of Geology or Mineralogy Any subject in the field of Ornithology

FRANCIS HARPER, Secretary.BOSTON SOCIETY OF NATURAL HISTORY, Boston, Mass., U. S. A. November, 1!928.

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xiiiSCIENCE-ADVERTISEMENTS

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