Excerpt from The Coal and Metal Miners' Pocketbook of Principles, Rules, Formulas, and Tables: Specially Compiled and Prepared for the Convenient Use of Mine Officials, Mining Engineers, and Students Preparing Themselves for Certificates of Competency as Mine Inspectors or Mine ForemanThe eighth edition of The Coal and Metal Miners' Pocket book is an exact reprint Of the seventh edition, issued to supply the demand while the ninth edition was being pared, and in which a number of changes will be made.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis 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.