The Disappearance of Images on Photographic Plates

Abstract

IT is the aim of the modern astronomer to employ photography, whenever possible, in the many branches of his work, as by this means the peculiarities of the observer are eliminated and a permanent record is obtained that can be examined at leisure at any later date. In some kinds of work photography helps us in obtaining a great number of facts in a very short space of time, facts which would have taken weeks to accumulate by the old method of eye observation. Not only is the science more rapidly advanced by the greater abundance of material at hand, and therefore available for discussion, but the application of photography to astronomy has opened up so many new fields of work that the whole subject has now a far wider horizon than before.