SOME OF THE RESULTS OF ASTRONOMICAL PHO- 

 TOGRAPHY PERTAINING SPECIALLY TO THE 

 WORK WITH A PORTRAIT LENS. 



(Plates I-VI.) 



By E. E. BARNARD. 

 {Read April 20, 1907.) 



In the present paper I wish to offer a few specimens of astro- 

 nomical photographs which have been made with portrait lenses. 

 These pictures, which are from my own work, are fair samples of 

 what can be done with this class of lens. They have been selected 

 to show the variety and extent of the work, which covers the Milky 

 Way, the nebulae, the larger star clusters, meteors, comets, the earth- 

 lit and the totally eclipsed moon, etc. Most of the pictures were 

 made with the lo-inch Brashear lens of the Bruce telescope of the 

 Yerkes Observatory. 



The Advantages of Photography in Astronomy. 



Before the application of photography to the study of the 

 heavens, one saw the sky but poorly indeed, and in the light of the 

 revelations of the photographic plate today, one is almost tempted to 

 say that he did not see the heavens at all, so vastly has photography 

 enlightened us as to the actual appearance of the sky and its 

 citizens. 



There are two causes that have helped to produce this wonder- 

 ful power that photography has given us. First, above all, the 

 great sensitiveness of the photographic plate over that of the human 

 eye. Second, the fact that our plates show us a vastly larger space 

 of the heavens than the visual telescope does — in some cases a 

 thousand times greater than is shown by our most powerful tele- 

 scopes of today. A wide field of view is of the utmost importance 

 in the study of the tails of comets, of the larger nebulas and of the 



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