New Alt-Azimuth Tables, 65° N. to 65° S

Abstract

SINCE the very general adoption of the method of navigation known as the Marcq system of position lines, in which, whatever the azimuth, the position line is determined by one and the same problem, the calculation of altitude, many attempts have been macTe so to simplify the working that the results can to a great extent be effected through the medium of suitably arranged tables by simple inspection. A fresh attempt of this nature forms a leading feature of the excellent little work recently issued by the Hydrographic Department at Tokyo. Like other tables of the kind, such as those of the Rev. F. Ball, R.N., and of Capt. Aquino, of the Brazilian Navy, Mr. S. Ogura, the inventor of the method, commences by assuming such a point upon the chart that latitude and hour-angle are each represented by an exact number of degrees. In the subsequent procedure, however, he differs wholly from the methods of his predecessors, and by means of but one special table, occupying only eighteen pages, carries out his purpose in a manner which, in point of simplicity, is certainly not inferior to anything that has gone before. A second table of about nine pages is added, but this is nothing more than a specially arranged table of logarithmic secants, convenient, but not in any way indispensable to the principle upon which the method is based.

New Alt-Azimuth Tables, 65° N. to 65° S.

Pp. xvii+154. (Tokyo: Hydrographic Department, 1920.)