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Tenth Edition, Revised

Professor of Landscape Gardening, Head of Department
Head of Division of Horticulture, Massachusetts Agricultural College

Including Many Chapters from Downing's “Rural Essays"
N presenting this new edition of Downing's "Landscape Gardening!' Professor Waugh has
directly on this important subject.

Those who have country places of their own, whether large or small, will appreciate the clearly written text-matter of this masterful work and the practical assistance it will give them in beautifying their grounds.

Downing & Waugh's “Landscape Gardening” has 439 pages, 6 by 9 inches, and is well illustrated, showing typical examples. Cloth-bound, $6.00 postpaid.

JOHN WILEY & SONS, Inc. 432 Fourth Avenue


Hom Intense Is Sunlight

Its intensity, of course, depends upon latitude, season, time of day, atmospheric conditions; but whatever it happens to be, it can be measured readily with

Leeds & Northrup Company's MACBETH ILLUMINOMETER

Illumination of any intensity, artificial or natural, is within the range of this useful instrument. Its scale reads foot-candles directly. It is provided with a reference standard lamp with which each observer standardizes the instrument according to his own visual perception. This is done wherever he happens to be-no photometric dark room is required.

The illustration shows one method for making a measurement. The illumination on the test-plate, mounted on a tripod, is being

measured. A translucent plate, mounted in
a "horn”, can be fitted to the instrument, and
by pointing the "horn”, in any direction, up,
down or sidewise, the illumination due to the
light from that direction is measured.
The Macbeth Illuminometer is especially

suited for investigations con-
cerned with the reactions of liv-
ing organisms to light.


Bulletin S680 describes the Macbeth Illuminometer in detail

Leeds & Northrup


Electrical Measuring Instruments 4901 Stenton Ave. Philadelphia, Pa.

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With Lippich Polarizer, adjustable half shadow angle, Scale can be accurately read to 1/100th degree.

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Repeated object lessons have demonstrated that nearly all progress in science has resulted in important advances in industry

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GE Research Laboratory

Schenectady, N. Y.

Among the many products developed by the General
Electric Company's research laboratories which are of
interest to manufacturers are the following:

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For further information address Supply Department, Schenectady Office.

General Electric



General Office
Schenectady, N.Y.

Sales Offices in all large cities


Instructive Books on Timely Subjects

Mysticism, Freudian- Sex and Sex Worship

ism and Scientific Psychology

By KNIGHT DUNLAP, Professor of Psychology at Johns Hopkins University, Baltimore. Author of “ Personal Beauty and Racial Betterment," etc. 150 pages, with special jacket. Price, $1.50.

By O. A. WALL, M.D., Ph.G., Ph.M., 625 pages,
6% x 944, with 375 beautiful illustrations, in-
cluding line drawings, half-tones. Beautifully
printed on special sepia paper with handsome
silk binding and gold stamping on backbone
and front cover. Price, cloth, postpaid, $8.50.
A Scientific Treatise on Sex, Its Nature and
Function, and Its Influence on Art, Science,
Literature, Architecture, and Religion-With
Special Reference to Sex Worship and Sym-
bolism. The first treatise that treats of Phallic
Worship and Symbolism in connection with the
evolution of the human body and mind.

This timely book analyzes the current Freudian movement in detail, and states in the light of analysis the fundamental principles of present day psychology. Written in popular style.

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0 You should order copies of these important books today through your bookseller or direct from the publishers. Also request a copy of our complete catalogue of medical, dental, scientific, pharmaceutical, and nursing publications. Mention “ Science” when writing or ordering.


THE C. V. MOSBY COMPANY 801-809 Metropolitan Building


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