306 PROCEEDINGS OF THE AMERICAN ACADEMY 



Whipple, a photographer of Boston, took the first recorded photograph 

 of the Moon. 



It is scarcely necessary to say that this first attempt was not a great 

 success, for then the art of photography was in its infancy. But it 

 was by no means a failure, and it at least proved that pictures of the 

 Moon could be taken, and gave a stimulus to further experiments. 

 The subject was afterwards taken up in England by Mr. Warren de 

 la Rue. To avoid the ditficulties arising from the imperfection of 

 refracting telescopes, which do not bring the visual and chemical rays 

 to the same focus, Mr. de la Rue employed a reflecting telescope ; and 

 with this instrument tolerably good results were obtained. 



Professor Henry Draper, of New York, employed the same method, 

 using a silvered glass reflector constructed by his own hands, and suc- 

 ceeded, it is believed, better than either of his predecessors. At this 

 period in the history of the application of photography to Astronomy, 

 Mr. Rutherfiird began his work. He also at first worked with sil- 

 vered reflectors, but after three months' trial abandoned them, and 

 devoted himself to the improvement of the refracting telescope. This 

 he accomplished in his earlier attempts by changing the curvatures of 

 the lenses composing the objective of the telescope, so that the com- 

 pound lens should give images of the requisite photographic sharpness 

 of definition. He subsequently accomplished the same object by using 

 an additional lens placed in front of the objective, and termed a cor- 

 recting lens. A great advantage of this method lay in the fact that, by 

 simply removing the correcting lens, the telescope could again be made 

 available for the ordinary methods of direct visual observation. With 

 a telescope so corrected, he obtained the magnificent pictures of the 

 Moon now so generally known and admired both in Europe and in this 

 country, — pictures which have not yet been equalled by those of any 

 other astronomer. He also succeeded in obtaining beautiful stereo- 

 graphs of the Moon, a feat which in Europe had been pronounced 

 impracticable. This he accomplished by taking the two 2:)hotogra23hs 

 of the Moon when in two different positions in her orbit, and when 

 these pictures combined give the most pex'fect stereoscopic relief. 

 Up to that time, stereographs of the Moon had been taken only 

 from plaster models. Having perfected the photographic telescope, 

 Mr. Rutherfurd turned his attention to stellar photography, and here 

 his higher scientific work begins. After many trials, he succeeded in 

 obtaining satisfactory pictures of groups of stars, embi'acing all those in 

 the field of the telescope, down to stars of the eighth or ninth magnitude. 

 Thus the group of the Pleiades afforded him a plate with 175 stars. 



