Excerpt from Railway Masonry and Bridge Foundations Most of the limestones are very suitable for pier and abutment work. They occur in layers of various thickness, the stone be ing very close grained and dressing freely. The blue limestone is very dense and weighs about the same as granite, which is 165 pounds to the cubic foot. The white and magnesian limestones are not so heavy, and when quarried are quite soft, more espe cially the magnesian, which can be cut with an ordinary pen knife, the same as chalk. Exposure to the air hardens either variety and they answer quite satisfactorily for railway work. Some limestones, however, have a tendency to slake and decompose on exposure to the air and water. 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.