Bøker av Silas W Holman

This comprehensive guide to the Telescope-Mirror-Scale method of testing and adjusting mirrors is a must-read for astronomers and hobbyists alike. With detailed instructions and diagrams, Silas W. Holman provides everything you need to know to ensure your telescope mirror is performing at its best.This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it.This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

An excerpt the PREFACE:IT would probably be within safe limits to assert that one-half of the time expended in computations is wasted through the use of an excessive number of places of figures, and through failure to employ logarithms. This waste might be almost wholly avoided by following a few simple computation rules and practising slightly with logarithm tables.The loss from the use of superfluous figures will be appreciated when it is considered that in direct or logarithmic multiplication and division with four, five, and six places of figures the work is respectively in the ratio of 1:2:3, or perhaps more nearly 2:3:4. Thus contrary to the fallacious excuse so commonly given that it is just about as easy to use six. or seven place tables as smaller ones, the work is doubled or trebled by the use of six places instead of four. Even the employment of six. or seven place tables, and dropping superfluous places when four or five are desired, causes much loss of time....