Excerpt from Steam Boilers The casing connecting the upper and lower shells is constructed of steel plate on an angle-iron frame, and lined with asbestos air-cell blocks to prevent the radiation of heat. The same form of covering is also used on top of the steam drum and on the bottom of the lower shell. With the exception of the tube sheets, all parts of the boiler, subjected to the pressure, are cylindrical or spherical in form, so that no stays are required, the heads being' supported by the tubes. 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.