Hansen's Improved Ex-Meridian Tables

Abstract

Journal seems rather unfair to Hansen, who is no longer able to defend himself. The book is not a new one-to my knowledge it has been in use for at least forty years-and the only major alteration in the revised form is the substitution of distance from the meridian (L.H.A.) in terms of arc instead of in terms of time, which is, of course, in accordance with modern practice. In all other respects the book is exactly as Captain Hansen compiled it. The purpose of the 'Explanation of the Tables' is to explain and illustrate the use of the tables: it is in Hansen's own words, and up to the present has been quite understandable to the average user. Examples are given of the different cases in which interpolation may be desirable or necessary, and examples of the appropriate steps to be taken are incorporated. The statement that the tables 'may be worked for half or fractional degrees without any interpolation whatever' is Hansen's own, as is the statement that 'it is never necessary to interpolate between two consecutive tables when they are equally accurate'. When they are not equally accurate, the more accurate table is used. The type of navigator that your reviewer knows well may not find that these tables will improve his navigation, but that is not Hansen's fault. In any case, it would not appear to be a valid reason why other navigators should be deprived of these very simple and helpful tables. 308 Birmingham Road, Yours faithfully, Walsall, C. W. T. Layton Staffs.