Publisher's Synopsis
Excerpt from A Practical Treatise on Land Surveying, or the Surveyor's Guide: Containing Practical Rules for Locating Lost Corners and Running Lines; How to Obtain the Variation of the Needle and Its Application, and Much Other Information of Practical Value to the Surveyor and the Public
Bear 111 mind no dependence can be placed in the needle readings, always run by back and fore sight-s equidistant from the instrument, the average of the readings (except there be energetic local attraction) will approximate the true course.
The importance of running by back and fore sights becomes apparent in observing the effect of Diurnal Variation. The variation of the needle increases from morn until the sun is at meridian height, when it decreases until at night it is the same original reading of the morning; hence at noon the needle reads from 6' to 15' more than at mom or eve. The departure for 15' measures 23 feet to the mile.
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.
