372 3Ir. A. A. Common [Feb. 26, 



The first important photograpli of the surface of the sun seems 

 to have been obtained by Dr. de La Rue, July 24th, 1861. 



The j^hotograph I show is one copied from a picture, itself a 

 reproduction, without retouch, of the original negative. 



(Photographs of the surface of the sun, by Janssen, were also 

 shown.) 



Berkowski, in the eclipse of the 28th July, 1851, took by the 

 daguerreotype the first photograph showing the corona and promi- 

 nences, and Dr. de la Eue in 1860 took the first good photographs 

 of the ^prominences, and obtained traces of the corona, using the 

 collodion process. 



In 1869, Professor Stephen Alexander obtained at Ollumwa the 

 first good photograjdjs of the corona. 



(Photographs of the corona and prominences, by General Tennaut, 

 Dr. de la Pue, and Captain Abney were shown.) 



Since this time, photography has been used at every total eclipse 

 that has been observed, with increasing success. 



In speaking of these corona photographs, I must not forget to 

 mention the important work of Dr. Huggins in photographing the 

 uneclipsed corona. He himself has lately given an account of the 

 methods he employs, and I have no doubt that under his skilful 

 direction we shall see the same successful advances as those we can 

 mark in every branch of astrcmomical photography ; although it is a 

 work which many of those who know the great difiiculties to be 

 encountered would hardly have dared to attempt. 



Photographs of the moon are so easy to obtain that she has 

 received more attention than any other celestial object ; yet, strange 

 to say, with less improvement, the j)ictures taken by Rutherford 

 more than twenty years ago, not being yet surpassed. 



Now, however, that we can safely enlarge the primary image 

 without unduly prolonging the exposure we may soon expect photo- 

 graphs of portions of the moon that will be far beyond anything 

 hitherto done, or possible, where the whole image is attempted. 



[Photographs of the moon, by Mr. Crookes, Dr. de la Rue, and 

 others, were shown.] 



With the stars photography has recently been most successful. 



Rutherford, in 1864, completed a photographic objective of 

 11 J inches aperture and 14 feet focal length, with which he obtained 

 some very fine photograi^hs. Some of his remarks, written in 1864,* 

 in connection with the future of astronomical photography, are so 

 interesting at the present time that I will repeat them. " Since 

 the completion of the photograjihic objective, but one night has 

 occurred (the 6th of March) with a fine atmosphere, and on that 

 occasion the instrument was occujued with the moon ; so that as yet 

 I have not tested its powers upon the close double stars, 2" being 



American Journal of Science anil Art,' 2nd series, vol. xxxix. p. 308. 



