Practical Astronomy
Kite Press | English | March 15, 2007 | ISBN: 140674607X | 296 pages | File type: PDF | 12 mb
Product Description
PRACTICAL ASTRONOMY A TEXTBOOK FOR ENGINEERING SCHOOLS AND A MANUAL OF FIELD METHODS BY GEORGE L. HQSMER Associate Professor of Geodesy, Massachusetts Institute of Technology THIRD EDITION NEW YORK JOHN WILEY SONS, INC. LONDON CHAPMAN HALL, LIMITED TA-5C 1 Observation on Polaris for Azimuth Frontispiece CCflPYRIGHT, 1910, 1917 AND 1925 BY GEORGE L. HOSMER PREFACE THE purpose of this volume is to furnish a text in Practical Astronomy especially adapted to the needs of civil-engineering students who can devote but little time to the subject, and who are not likely to take up advanced study of Astronomy. The text deals chiefly with the class of observations which can be made with surveying t instruments, the methods applicable to astronomical and geodetic instruments being treated b t briefly. It has been the authors intention to produce a book hich is intermediate between the text-book written for the student of Astronomy or Geodesy and the short chapter on the subject generally given in text-books on Surveying. The subject has therefore been treated from the standpoint of the engineer, who is interested chiefly in obtaining results, and those refinements have been omitted which are beyond the requirements of the work which can be performed with the engineers transit. This has led to the introduction of some rather crude mathematical processes, but it is hoped that these are presented in such a way as to aid the student in gaining a clearer conception of the prob lem without conveying wrong notions as to when such short-cut methods can properly be applied. The elementary principles have been treated rather elaborately but with a view to making these principles clear rather than to the introduction of refiner ments. Much space has been devoted to the Measurement of Time because this subject seems to cause the student more difficulty thar y other branch of Practical Astronomy. The attempt has I v J made to arrange the text so that it will be a convenient reference book for the engineer who is doing field work. For convenience in arranging a shorter course those subjects ill iv PREFACE which are most elementary are printed in large type. The mat ter printed in smaller type may be included in a longer course and will be found convenient for reference in field practice, par ticularly that contained in Chapters X to XIII. The author desires to acknowledge his indebtedness to those who have assisted in the preparation of this book, especially to Professor A. G. Robbins and Mr. J. W. Howard of the Massa chusetts Institute of Technology and to Mr. F. C. Starr of the George Washington University for valuable suggestions and crit icisms of the manuscript. G. L. H. BOSTON, June, 1910. PREFACE TO THE THIRD EDITION THE adoption of Civil Time in the American Ephemeris and Nautical Almanac in place of Astronomical Time in effect in 1925 necessitated a complete revision of this book. Advantage has been taken of this opportunity to introduce several improve ments, among which may be mentioned the change of the no tation to agree with that now in use in the principal textbooks and government publications, a revision of the chapter on the different kinds of time, simpler proofs of the refraction and parallax formulae, the extension of the article on interpolation to include two and three variables, the discussion of errors by means of differentiation of the trigonometric formulae, the in troduction of valuable material from Serial 166, U. S. Coast and Geodetic Survey, a table of convergence of the meridians, and several new illustrations. In the chapter on Nautical As tronomy, which has been re-written, tfee method bf Marcq Saint-Hilaire and the new tables H. O. 201 and 203 for laying down Sumner lines are briefly explained. An appendix on Spherical Trigonometry is added for convenience of reference.
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