Mr. Merrifield's “Treatise on Nautical Astronomy”

Abstract

THIS is an excellent work for the student, evidently compiled with considerable care, which may also be consulted with advantage by the seaman. Of course the author does not claim originality, excepting in one particular, viz. a method of his own for “clearing the lunar distance,” as, in point of fact, nearly everything the work contains has been published in previous treatises. Mr. Merrifield deserves, however, the credit of placing clearly before the student many points which are only touched on by other writers—notably the account of the correction for refraction, and the explanation of the fact that the maximum altitude is not invariably the meridian altitude, a point which is only touched on by a footnote in Raper, and is usually ignored entirely; yet which is of considerable importance in the case of the moon. The examples, also, which are given at the end of each chapter are of great use to the student, as from them a knowledge is obtained of the subjects he is likely to be examined in o and as these questions have been selected from many examination papers, they are an excellent guide. In the theoretical part of nautical astronomy the book is nearly all that can be desired, and this part can always be learnt better on shore than in a ship, where the constant noise and interruption, together with perpetual motion at sea, renders study all but impracticable: in one or two cases, however, Mr. Merrifield also touches on the practical use of instruments, &c., and on these subjects he is naturally not so good an authority. It may perhaps, therefore, be advisable to point out the usual course of proceedings in Her Majesty's surveying-vessels, both in correcting instruments and also in ascertaining positions at sea.

A Treatise on Nautical Astronomy for the Use of Students.

By John Merrifield (London: Sampson Low, Marston, Searle, and Rivington, 1886.)