Download or read book Tables of Calculated Hour-Angles and Altitude Azimuth Table 30 N. To 30 S., Ex-Meridian Tables 70 N. To 70 S written by Harold S. Blackburne and published by Forgotten Books. This book was released on 2018-03-30 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from Tables of Calculated Hour-Angles and Altitude Azimuth Table 30 N. To 30 S., Ex-Meridian Tables 70 N. To 70 S: Calculated Reductions and Azimuths of 30 Bright Stars From 1 Hour to 3 Hours From Meridian 64 N. To 60 S The main purpose of these tables is to make as easy as possible the problem of finding the ship's position from combined altitudes of sun, moon, or stars, and especially to encourage the at present much neglected and apparently little valued practice of determining the ship's position from two or three stars at twilight, a few minutes before sunrise, and a few minutes after sunset. The writer, having made a regular practice of such observations for several years of his sea life, is fully alive to the great value of the problem, and considers it to be the most valuable problem in navigation, and has consequently for the last thirty and odd years deplored the neglect of the authorities to give it in the Board of Trade examination for masters and mates. It ought to be the rule, instead of the rare exception, in all seagoing steamers to take such observations daily. In spite of the discouragement I have received from those whom I might most naturally have expected to help and encourage me, and the continued Opposition of the authorities to the use of my tafiles and methods in the examination room, it will be seen that I have not yet given up my efforts to stir up and encourage shipmasters and officers to get out of the rut of relying Wholly on their morning longitude and noon latitude position, and am still working to make easier and more popular the above-mentioned problems, and I have been much encouraged of late to find that my methods and tables are now being very generally used by the younger generation of officers, at any rate in the ships which trade regularly to New Zealand, and even by some of our coasting shipmasters. My greatest incentive, however, to continued effort in this direction has been the knowledge that such observations tend greatly to the saving of lives and ships from destruction. In the course of my duties in the investigation of witnesses' evidence in wreck inquiry cases in New Zealand, I was struck by the fact that within three years no less than three ships were wrecked, and many lives lost, which would in all probability have been saved had the officers been in the habit of determining the ship's position by simultaneous observations of two stars at twilight but no Court of Inquiry could justly censure the master for neglect to take such observations when the determina tion of this problem is not provided for in the Board of Trade examination for either the mate or master. At about the same time I also received letters from two shipmasters gratefully acknowledging the value that my books had been to them, and telling me that the determination of their ship's position by stellar observations (after experiencing exceptionally strong currents) had been the means of saving their ships from great risk of stranding, one in the China Sea, and the other in the Bay of Bengal. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.