Excerpt from Smithsonian Miscellaneous Collections, Vol. 95 If solar observations could be made on the moon, the readings of a silver-disk pyrheliometer alone would give us the solar constant. Since this is impossible, we may approximate the solar constant by making radiation measurements at different altitudes. The highest observations made heretofore with the silver-disk pyrheliometer were those taken by Dr. C. G. Abbot on Mount Whitney, feet. 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 techlogy 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.