Prof. Barnard's Astronomical Photographs ¹

Abstract

THE name of Barnard is not only familiar to all astronomers, but also very generally to those who have from time to time perused illustrated astronomical books. The photographic recording of celestial objects has been carried by him to a very high state of perfection, and thereby not only has his own fame and that of the Lick Observatory been considerably enhanced, but our knowledge of the visible and invisible universe has been greatly extended. Unfortunately, it is an extremely difficult matter to reproduce, with complete accuracy, such photographs as are obtained by the combination of a telescope and a photographic plate, for not only doâ delicate lights and shades become relatively altered, but other errors may and do creep in during the process of reproduction. Further, the attempt to secure such high accuracy in reproduction increases very considerably the cost of publication. It will be gathered, therefore, that the extreme fineness and beauty of the original pictures cannot necessarily be judged by plates that have so far been published.