Back MatterSource: The Scientific Monthly, Vol. 56, No. 4 (Apr., 1943), pp. v-viPublished by: American Association for the Advancement of ScienceStable URL: http://www.jstor.org/stable/17931 .

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THE SCIENTIFIC MONTHLY v

"WMratten Light Filters"

A BOOK OF DATA ON ATTEN FILTERS

THERE ARE more than 100 filters in the series of Wratten light filters. They are designed for use in general mono- chrome and color still photography, cinematography, and special scientific fields-including astronomy, photome- try, spectroscopy, photomicrography.

Eachl Wratten Filter is made to meet a rigid standard, and is supplied in the form most convenient for its appli- cation. The purpose of the book, Wratten Light Filters, is to facilitate selection of filters by providing complete spectrophotometric data concerning them.

The 88-page Sixteenth Edition of this publication gives transmission curves and tables for all filters, as well as notes on the use of filters for special purposes. It is avail- able at dealers in photographic supplies.

EASTMAN KODAK COMPANY Research Laboratories Roehester, N. Y.

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vi THE SCIENTIFIC MONTItLY

F: F]i

Wlhat's a cotangent got to do with ack-ack?

PLENTY. So have sines, cosines, squares and square

roots, differential equations, and integral calculus.

For the accurate firing of anti-aircraft batteries depends wholly upon the science of mathematical calculations that must be made fast-faster than a score of the most brilliant mathematicians could do it!

To solve these problems-to make the ack-ack of the United Nations deadlier-Westing- house engineers are assisting in the development of an im- proved "electric brain" that

makes the necessary lightning- like calculations.

The firing control-known as the "computing director"- not only locates the exact posi- tion of the target as it twists and dodges through the sky. It also calculates where the enemy plane will be by the time the shell has traveled 10,000 or more feet into the air-all in a matter of seconds!

And that's not all! The com- puting director makes instan- taneous corrections for drift, air density, wind conditions, and gun-muzzle velocity. In

addition, it calculates the fuse setting on the shell-so that the burst will occur at the calculated position of the enemy plane.

Westinghouse is making hundreds of other weapons for victory such as: guns, shells, radio equipment, instruments, electric motors and generators, and propulsion equipment for our giant battleships and rapidly growing merchant marine. And delivering these war materials faster than ever!

We are proud of the way Westinghouse "know-how" is adding day-by-day to Ameri- ca's tremendous striking power -on land, at sea, and in the air!

Westinghouse Electric & Manufacturing Company, Pittsburgh, Pennsylvania.

Westinghouse PLANTS IN 25 CITIES ...............OFFICES EVERYWHERE

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A New Textbook __ _

HILL and KELLEY

] Organic Ckemistry Prepared for a rigorous full year's college course in organic chemistry, the aim of this new text is to develop a balanced presentation of the theoretical aspects of organic chemistry, of the properties, methods of preparation and reactions of compounds, of the I.U.C. system of nomenclature and its rela- tion to earlier systems, and of the physiological effects and uses of organic compounds. Both graphic and structural formulas are provided. Ques- tions and problems are given at the end of each chapter. By G. A. Hill, Wesleyan IUniversity and Louise Kelley, Goucher College. 919 Pages. $4.00 (1943)

THE BLAKISTON COMPANY, Philadelphia

FIJUORINE AND DENTAL HEALTH viii + 101 pages (' x 10j), illustrated, 11 contributors, references,

cloth bound, published in 1942.

As a public.health problem, dental fluorosis is rapidly assuming large proportions. Ex- amination of sources of water for domestic use for fluorides is becoming a routine require- ment, analogous to bacteiiological examinations a few decades ago.

From the scientific point of view dental fluorosis is a new and quite different illustration of the fact that very minute quantities of certain elements and certain organic compounds sometimes have eXxtraordinary effects upon living organisms. A peculiarity of fluorine is that, so far as is known at present, its ingestion from natural sources produces sensible biological effects only upon the teeth-apparently beneficial ones if in quantities that are somewhat below well-determined limits and certainly tragically harmful ones if well-known limits are exceeded.

Rarely is the entire history of a scientific subject covered so completely as in this volume, and rarely do the contributors include so nearly all who have carried out fundamental investi- gations on which the conclusions are based. This happy situation is due to the fact that the cause of what is known as dental fluorosis is of recent discovery, so recent that the whole subject is still expanding and its ramifications are rapidly becoming numerous.

Price, $3.00; special price to members of the Association on request.

American Association for the Advancement of Science Smithsonian Institution Building

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Physics and Philosophy

By SIR JAMES JEANS

This new book discusses that borderland territory between physics and philoso- phy which has become so interesting and important through recent develop- ments of theoretical physics. A review of the philosophical thought from the time of the Greeks, and an account of the progress of physics since the time of Newton show how modern theories of physics closely touch our lives and affect our ways of thought on religion, free-will, and the nature of man. The whole book is written with the lively sparkle that marks all that Sir James writes.

Ready March 16th. $2.75 (probable)

Vertebrate Photoreceptors

By SAMUEL R. DETWILER

This monograph presents a general account of the visual cells of vertebrates with particular emphasis upon their structure, development, distribution, and certain aspects of their physiology. It will be a valuable handbook for all concerned with problems of retinal physiology or for anyone with a general interest in the biology of the retina.

The visual ability of animals and their habits of life are discussed in relation to the presence or absence of rods and cones, as well as their relative distribution in the eyes of different forms. The structure, occurrence, functional signifi- cance, and evolutionary relationships of the fovea centralis receive special attention. Full attention is also given to the role of vitamin A in vision. Retinal photopigments, night blindness and restorative therapy, and the pos- sibilities for structural regeneration of damaged rod visual cells due to pro- longed vitamin A-deficiency are all thoroughly treated in the light of recent investigations.

Ready March 30th. Illustrated. $4.00 (probable)

The Macmillan Company, 60 Fifth Ave., New York

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