A NAVIGATORS BOOK.

Evening Star, Issue 13031, 15 August 1908, Page 2

A NAVIGATORS BOOK.

An instructive insight to the valuable work effected by the New Zealand Marine Department is afforded by a perusal of a seafarer's book of azimuth' and ex-meridiar. tables, compiled by Captain H. S. Blackburne, nautical adviser to the Government, and Mr Charles Westland, of Glen Muick, Civnterbury, and published by the direction of the Minister of Marine. The compilation of innumerable tables is clear, concise, and well-arranged, and should prove a storehouse of useful information to practical navigators, providing to them a short, easv road to accurate calculation. 'ln addition to numerous tables for azimuth, great circle sating, and reduction to the meridian, with a new and improved 'Sumner" method, there are many useful navigation tables. It is pointed out in the preface that most exmeridian tiibies are conlked .to the observation near the upper meridian. of the latest and best of Mich v.oik (Davis's ep-en-did tables) is no exception to this rule. " \V<> have therelore," says the author, " e:i deavored to make up for this mission by special calculation ot the reduction collection from the inferior transit. The reduction corrections and azimuths of seventeen of the brightest circumpolar stars have beer, calculated to 75min from the bdow pole meridian, and for a few of the very bright circumpolar stars the azimuth has been calculated for every two minutes up to three hours from the meridian." Tne» habitual use of the book and adherence to the methods recommended should reduce the cases of miscalculation to a minimum. The valuable work should be a po-5«6.-.';on of all mariners.