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Theory of Errors and Least Squares

By LEROY D. WELD, Professor of Physics in Coe College
Cloth, 12mo, 190 pages. $1.25

Scientific research in universities and graduate schools is rapidly reviving, as the National Research Council's recent announcement of numerous fellowships in physics and chemistry clearly indicates. The Method of Least Squares provides the research worker with a mathematical implement of the greatest usefulness; and the Theory of Errors has direct bearing upon very important laws and theories, not only in physics, chemistry and astronomy, but in biology and psychology as well. Professor Weld presents this material in a simple and concise form which may be easily mastered and promptly put into practice.

CONDENSED TABLE OF CONTENTS

Chapters: I. On Measurement. II. On the Occurrence and General Properties
of Errors. III. On Probabilities. IV. The Error Equation and the Principle
of Least Squares. V. On the Adjustment of Indirect Observations. VI. Em-
pirical Formulas. VII. Weighted Observations. VIII. Precision and the
Probable Error. Appendix.

"The treatment is remarkably clear and well-ordered. The topics are nicely correlated. The numerous, excellent, well-chosen exercises at the end of each chapter will, if solved, greatly enhance the permanent value of the book."-From Science. Every intelligent observer desires some concrete expression of the quality of his observations; the computer who has to combine the results of different series of observations should have some knowledge of their relative accuracy in order to assign to each series its proper weight; and the investigator engaged in a complicated series of experiments desires some criterion by which to estimate the relative errors of the several parts of his work and to apportion properly his care among them. Experienced judgment will go a great way, but the working method of least squares, which has been developed on the basis of experience and analysis into its present form by a succession of thinkers, presents clearly the safest means of obtaining the result of highest probability from a given set of observations and provides methods for appraising the accuracy of such a result and for expressing this accuracy vividly to others. The present volume is planned with the purpose of making the elements of the theory of errors and least squares easily attainable both by students and by research workers. It will prove useful in the classroom, in reference libraries and also on the desk."-From American Mathematical Monthly.

IN PREPARATION

A Short Course in Mathematics
By R. E. MORITZ, Professor of Mathematics, Univer-
sity of Washington. Cloth, 12mo, about 248 pp.

A text containing the material essential for a short course in Freshman mathematics which is complete in itself, and which contains no more material than the average Freshman can assimilate. The book will constitute an adequate preparation for further study, and will enable the student to take up the usual course in analytical geometry without any handicap.

Among the subjects treated are: Factoring, Radicals, Fractional and Negative Exponents, Imaginary Quantities, Linear and Quadratic Equations, Coordinates, Simple and Straight Line Graphs, Curve Plotting, Maxima and Minima Areas, The General Angle and Its Measures, The Trigonometric or Circular Functions, Functions of an Acute Angle, Solution of Right and Oblique Triangles, Exponents and Logarithms, Application of Logarithms to Numerical Exercises, to Mensuration of Plane Figures, and to Mensuration of Solids, The Four Cases of Oblique Triangles, Miscellaneous Problems Involving Triangles. The book will be ready for examination during the summer.

IN PREPARATION

Plane Trigonometry

By JOHN W. YOUNG and FRANK M. MORGAN, Professors of Mathematics in Dartmouth College. Cloth, 12mo, about 130 pages.

In their earlier work "Elementary Mathematical Analysis" Professors Young and Morgan gave to the branches of mathematics commonly studied in first-year courses at college-advanced algebra, trigonometry, and analytical geometry-a unity which produced added interest in the subject on the part of both students and instructors. The book aroused widespread interest and approval, and it has been adopted very extensively as a text. So favorable has been the comment on the portions of the book which deal with trigonometry that the authors have prepared a new Trigonometry, supplementing the excellent material drawn from the earlier book by new portions which make the work a complete and original text-book in Plane Trigonometry. This new book will be ready for examination during the summer. It will be bound both with and without logarithmic and trigonometric tables.

The Macmillan Company, Publishers

New York

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IN PRESS

List of Coleoptera, or Beetles, of North America

By CHARLES W. LENG

An important and long needed work of reference for all workers, students and collectors interested in this favorite order of insects: embracing

I. A complete list of the described species, forms, and varieties, including synonyms, with page reference to place of original description.

II. A complete list of works containing original descriptions of North American species from 1758 to the present time.

III. A complete list of the Fossil North American forms, prepared by Professor H. F. Wickham.

Also A general sketch and outline of the various systems of classification proposed in recent years.

The book will be in every way a worthy successor of the well known Henshaw "Check List" issued in 1885, with its three supplements, the most recent of which was issued in 1895. The addition of bibliography, though necessarily in somewhat condensed form, will make the new Leng list indispensable and invaluable to all those interested in any way in North American Beetles.

The work should be in every reference library.

This will be a work of about 500 pages, 75% inches by 1034 inches, printed mostly in double column, with ample margins for annotations. It is to be printed by the well known Cosmos Press of Cambridge, Massachusetts, printers for the Museum of Comparative Zoology, American Museum of Natural History, and other scientific institutions.

Subscription Price (Including Delivery)

Unbound, Five Dollars and Fifty Cents. Substantially bound in buckram, Six Dollars and Fifty Cents. A small number of copies, unbound, will be issued printed on one side only, Price, Seven Dollars. Subscriptions are payable in advance.

Publication date, about September 1st, 1919, at which time the price will be advanced two dollars.

Send all subscriptions and remittances to the publisher

JOHN D. SHERMAN, Jr.

24 Claremont Avenue

Mount Vernon, New York

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SCIENCE

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FIFTY YEARS OF THE AMERICAN MUSEUM OF NATURAL HISTORY Ir has become necessary to postpone the celebration of the fiftieth anniversary of the charter of the museum for five years, namely, until 1924. It is hoped that this celebration may be marked by the completion of the entire southern half of the museum, as planned between 1870 and 1875, as the year 1924 will mark the period of half a century since the building was actually begun by the City of New York.

In the meantime at the request of the editor of SCIENCE, there is here presented a review of certain aspects of the development of the institution during its first fifty years, based on the Annual Report of the president to the trustees.

The American Museum has broken away from many old museum traditions and customs and has been constantly striking out along new lines in every branch of its activity. In exploration, while making North America our chief concern, we have reached out into South America, Africa, Asia, and, in certain branches, into Europe itself. The natural history of our new colonial wards, the Philippines and Porto Rico, are matters of intimate concern. In South America, through a series of expeditions we are exploring every part of the continent and have established most cordial personal as well as scientific relations.

This is in keeping with the world-wide extension of American interests and influence and is part of the inevitable participation of America in the world's affairs. Neither the American Museum, nor our government, nor our people can remain isolated or bound by the confines of our own continent. Thus, while more than ever an American Museum, our institution has become a world museum. In increasing degree it is bringing all parts of the world within the view of the millions

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