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COPYRIGHT, 1888, 1899, BY G. A. WENTWORTH

COPYRIGHT, 1910, 1911, 1913, BY GEORGE WENTWORTH
AND DAVID EUGENE SMITH

ENTERED AT STATIONERS' HALL

ALL RIGHTS RESERVED

PRINTED IN THE UNITED STATES OF AMERICA

229.10

HARVARD
UNIVERSITY
LIBRARY

46*217

The Athenæum Press

GINN AND COMPANY. PRO-
PRIETORS BOSTON U.S.A.

PREFACE

Long after the death of Robert Recorde, England's first great writer of textbooks, the preface of a new edition of one of his works contained the appreciative statement that the book was "entail'd upon the People, ratified and sign'd by the approbation of Time." The language of this sentiment sounds quaint, but the noble tribute is as impressive to-day as when first put in print two hundred and fifty years ago.

With equal truth these words may be applied to the Geometry written by George A. Wentworth. For a generation it has been the leading textbook on the subject in America. It set a standard for usability that every subsequent writer upon geometry has tried to follow, and the number of pupils who have testified to its excellence has run well into the millions. In undertaking to prepare a work to take the place of the Wentworth Geometry the authors have been guided by certain well-defined principles, based upon an extended investigation of the needs of the schools and upon a study of all that is best in the recent literature of the subject. The effects of these principles they feel should be summarized for the purpose of calling the attention of the wide circle of friends of the Wentworth-Smith series to the points of similarity and of difference in the two works.

1. Every effort has been made not only to preserve but to improve upon the simplicity of treatment, the clearness of expression, and the symmetry of page that characterized the successive editions of the Wentworth Geometry. It has been the purpose to prepare a book that should do even more than maintain the traditions this work has fostered.

2. The proofs have been given substantially in full, to the end that the pupil may always have before him a model for his independent treatment of the exercises.

3. The sequence of propositions has been improved in several respects, notably in the treatment of parallels.

4. To meet a general demand, the number of propositions has been decreased so as to include only the great basal theorems and problems. A little of the less important material has been placed in the Appendixes, to be used or not as circumstances demand.

5. The exercises, in some respects the most important part of a course in geometry, have been rendered more dignified in appearance and have been improved in content. The number of simple exercises has been greatly increased, while the difficult puzzle is much less in evidence than in most American textbooks. The exercises are systematically grouped, appearing in full pages, in large type, at frequent intervals. They are not all intended for one class, but are so numerous as to allow the teacher to make selections from year to year.

6. The work throughout has been made as concrete as is reasonable. Definitions have been postponed until they are actually needed, only well-recognized terms have been employed, the pupil is initiated at once into the practical use of the instruments, some of the reasons for studying geometry are early shown in an interesting way, application of geometry to practical cases in mensuration is provided for, and correlation is made with the algebra already studied.

The authors are indebted to many friends of the WentworthSmith series for assistance and encouragement in the labor of preparing this work, and they will welcome any further suggestions for improvement from any of their readers.

GEORGE WENTWORTH
DAVID EUGENE SMITH

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