IF the reason be demanded for the appearance of another book on Field Astronomy when there are already published several excellent works on the subject, it may be stated as follows: That although any one of them may serve very well as a text for a comparatively extended study, the author has been unable to find one sufficiently concise to fit the short time usually al lowed for the work in a civil engineering course which would still provide enough of the fundamentals of the subject to enable the reader to make, intelligently, the observations and accom panying computations required in the practice of general engineer ing and surveying. Something is needed more complete than the usual °chapter in books on surveying and less extensive than most texts on field astronomy. This need, which is acknowledged by other teachers to exist, it is hoped to fill; and at the same time it has been attempted to provide a book which will be of service to engineers and surveyors whose practice requires that they occasionally make astronomical Observations. To this end the discussion of fundamentals has been made brief, but it is thought sufficiently thorough for the purpose. Special attention has been given to the matter of measurement of time, because it is believed that this causes more difficulty for students in general than any other part Of the subject.
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