Publisher's Synopsis
Excerpt from Summary of the Course of Permanent Fortification: And of the Attack and Defence of Permanent Works, for the Use of the Cadets of the U. S. Military Academy
The numbers which express the dis tances of the lines from the plane of comparison, are termed references. The unit in which these distances are expressed, is usually the linear foot and its decimal divisions.
As the position assumed for the plane Of comparison is arbitrary, it may be taken either above or below every point of the surface to be projected.
In the French military service, it is usually taken above; in our own, below the surface. The latter seems the more natural and is more convenient, as vertical distances are more habitually estimated from below upward than in the contrary direction. Each Of these methods has the advan tage Of requiring but one kind of symbol to be used, viz the numerals expressing the references; Whereas, if the plane of comparison were SO taken that some of the lines projected should lie on one side of it and some on the other, then it would be necessary to use, in connection with the references, the algebraic symbols plus or minus, to designate those lines above the plane from those below it.
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.
