The purpose of this article is to describe the new tables, with the above title, which are shortly to be published by the U.S. Naval Oceanographic Office as H.O. Pub. No. 229.

Historical Survey. The most comprehensive tables designed for the application of the intercept method of plotting position lines in the practice of astronomical navigation at sea are the well-known Tables of Computed Altitude and Azimuth, originally published in the years 1936–1945 as H.O. Pub. No. 214 by the U.S. Navy Hydrographic Office (as it was then called). These are by no means the earliest of such tables in concept and objective, for Lord Kelvin, generally considered the father of modern navigation methods, expressed interest in tables from which solutions could be extracted direct; he recognized, however, that the tabulation of 903 × 603 or 157,464,000,000 solutions, which would be required to avoid interpolation, was quite impracticable.