president's address SECTION A. 71 



possible in a hundred years by older methods. Its whole life history 

 covers but fifty-three years, and its infancy and youth were cramped 

 by the want of means of existence and growth ; but its latter years 

 have been marked by a Adgor which has done so much that I shall 

 have little more than time to mark the stepping-stones in that 

 onward march ; to trace the details would take volumes. 



Fifty-three years ago photography was in the daguerreotype 

 stage, when it was just possible to get a rough photograph of the 

 moon ; forty-three years ago it had reached the collodion stage, 

 and was capable of rendering great aid to astronomy. Its worth 

 had been proved, and the conditions of its successful application to 

 the wants of the astronomer were known, but the enormous value of 

 that power was somehow overlooked. Was it that the innovation 

 was too great to be accepted at once, or that they did not consider 

 the matter sufficiently ? If the following record of the slow progress 

 that followed that time and the gradually accelerating progress of 

 the last few years should enlist some other worker into the army 

 of astronomers, it will have done something to add to our know- 

 ledge. 



It is generally stated that astronomical photography began when, 

 in 1850, Professor Bond succeeded in taking daguerreotypes of the 

 moon with the great loin, refractor at Harvard College Observa- 

 tory, but there seems to be no doubt that impressions of the moon 

 were obtained with more or less success some ten years earlier. 

 Professor Henry Draper, of the New York University, writes'^ : — 

 " The first photograph of the moon was taken by my father. Professor 

 •I. W. Draper, M.D., who published notices of them in his quarto 

 work on the forces of organised plants, and in the Philosophical 

 Magazine. The specimens were about lin. in diameter, and were 

 presented to the Lyceum of Natural History of New York. They 

 were taken with a photographic lens of 5in. in aperture, furnished 

 with an eyepiece to increase the magnifyino^ power, the whole 

 mounted on a polar axis and moved by clockwork ; the time of 

 exposure was twenty minutes." In September, 1840, he writes : — 

 " There is no difficulty in procuring an impression of the moon bv 

 dagueireotype beyond that which arises from her motion." This 

 was not his first attempt to apply photography to astronomical 

 work, for he tried in 1834 to fix the lines of the spectrum. The 

 sensitive surface used was bromide of silver as a coating on 

 paper. The experiment was not a success, but it is mentioned in 

 the Philosophical Magazine for 1843, " and in the summer of 1842, 

 simultaneously with M. Becqueret, by using daguerreotype plates, 

 I succeeded, and in the following March sent a drawing of the 

 photograph to the Philosophical Magazine, and in 1843 I made 

 photographs of the diffraction spectrum by a grating both by 

 reflection and transmission." 



Arago announced to the Academic of Sciences at Paris on the 

 13th of August, 1839^, the great discovery of Niepce and Daguerre, 



