REFERENCE LIBRARY A SERIES OF TEXTBOOKS PREPARED FOR THE STUDENTS OF THE IN PERMANENT FORM THE INSTRUCTION PAPERS, EXAMINATION QUESTIONS, AND KEYS USED ARITHMETIC LOGARITHMS GEOMETRICAL DRAWING 76-8221 SCRANTON INTERNATIONAL TEXTBOOK COMPANY Copyright, 1897, 1898, 1899, by THE COLLIERY ENGINEER COMPANY. Copyright, 1904, 1906, by INTERNATIONAL TEXTBOOK COMPANY. Entered at Stationers' Hall, London. Arithmetic, Sections 1, 2, 3, 4, and 6: Copyright, 1892, 1893, 1894, 1895, 1896, 1898, 1899, Arithmetic, Section 5: Copyright, 1905, by INTERNATIONAL TEXTBOOK COMPANY. Elements of Algebra: Copyright, 1893, 1894, 1895, 1896, 1898. 1900, by THE COLLIERY Logarithms: Copyright, 1897, 1898, by THE COLLIERY ENGINEER COMPANY. Plate, Projections-I: Copyright, 1893, 1894, 1896, 1897, 1898, by THE COLLIERY ENGI Plate, Projections-II: Copyright, 1893, 1891, 1896, 1897, 1898, by THE COLLIERY ENGINEER COMPANY. Plate, Conic Sections: Copyright, 1893, 1894, 1896, 1897, 1898, by THE COLLIERY Plate, Intersections and Developments: Copyright, 1893, 1894, 1897. 1898. by THE Arithmetic, Key: Copyright, 1893, 1894, 1896, 1897, 1898, by THE COLLIERY ENGINEER Logarithms, Key: Copyright, 1897, by THE COLLIERY ENGINEER COMPANY. All rights reserved. PRINTED IN THE UNITED STATES BURR PRINTING HOUSE FRANKFORT AND JACOB STREETS NEW YORK PREFACE Formerly it was our practice to send to each student entitled to receive them a set of volumes printed and bound especially for the Course for which the student enrolled. In consequence of the vast increase in the enrolment, this plan became no longer practicable and we therefore concluded to issue a single set of volumes, comprising all our textbooks, under the general title of I. C. S. Reference Library. The students receive such volumes of this Library as contain the instruction to which they are entitled. Under this plan some volumes contain one or more Papers not included in the particular Course for which the student enrolled, but in no case are any subjects omitted that form a part of such Course. This plan is particularly advantageous to those students who enroll for more than one Course, since they no longer receive volumes that are, in some cases, practically duplicates of those they already have. This arrangement also renders it much easier to revise a volume and keep each subject up to date. Each volume in the Library contains, in addition to the text proper, the Examination Questions and (for those subjects in which they are issued) the Answers to the Examination Questions. In preparing these textbooks, it has been our constant endeavor to view the matter from the student's standpoint, and try to anticipate everything that would cause him trouble. The utmost pains have been taken to avoid and correct any and all ambiguous expressions-both those due to faulty rhetoric and those due to insufficiency of statement or explanation. As the best way to make a statement, explanation, or description clear is to give a picture or a |