Excerpt from Spectrum Analysis in Its Application to Terrestrial Substances, and the Physical Constitution of the Heavenly Bodies This was so evident to the late Dr. Schellen, that when a third edition of his valuable book was called for, he set himself the task of reconstructing the whole work, as in no other way could the mass of new material he had accumulated be fittingly introduced. While thus engaged he was attacked by the lingering illness to which unhappily he has recently succumbed, and which obliged him, for the satisfactory completion of his labours, to seek a coadjutor in his'esteemed friend Dr. H. J. Klein. 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.