on celestial photography in england. 131 



Part 1. 

 Historical Outline. 



The late Professor Bond of Cambridge, in conjunction with Messrs. 

 Whipple and Black of Boston in the United States, was the first to make 

 a photographic picture of any celestial body. By placing a daguerreotype 

 plate in the focus of the great refractor of the Harvard Observatory, of 

 15 inches aperture, he obtained a daguerreotype of our satellite. This was, 

 I believe, about the year 1850, for 1 remember seeing one of these pictures 

 in the Exhibition of 1851, and some were exhibited at the meeting of the 

 Royal Astronomical Society in May 1851. The experiments were discon- 

 tinued after a time in consequence of irregularities in the going of the 

 clock-work driver, and were not resumed again till 1857, when new clock 

 machinery was attached to the telescope*. 



At the latter end of 1852, I made some successful positive lunar photo- 

 graphs in from ten to thirty seconds on a collodion film, by means of an 

 equatorially mounted reflecting telescope of 13 inches aperture, and 10 feet 

 focal length, made in my workshop, the optical portion with my own hands ; 

 and I believe I was the first to use the then recently discovered collodion in 

 celestial photography f. In taking these early photographs, I was assisted 

 by my friend Mr. Thornthwaite, who was familiar with the employment of 

 that new medium J. At that period, I had not applied any mechanical 

 driving motion to the telescope, so that I was constrained to contrive some 

 other means of following the moon's apparent motion ; this was accomplished 

 by hand ; in the first instance, by keeping a lunar crater always on the wire 

 of the finder by means of the ordinary hand-gear of the telescope, but after- 

 wards by means of a sliding frame fixed in the eye-piece holder, the motion 

 of the slide being adjustable to suit the apparent motion of our satellite ; the 

 pictorial image of the moon could be seen through the collodion film, and could 

 be rendered immoveable in relation to the collodion plate, by causing one 

 of the craters to remain always in apparent contact with a broad wire 

 placed in the focus of a compound microscope, affixed at the back of the 

 little camera box, which held the plate. Although these photographs were 

 taken under the disadvantage referred to, namely, the want of an automatic 

 driving motion, excellent results were nevertheless obtained, which proved 

 how perfectly the hand may be made to obey the eye. I could not take 

 photographs of the moon in this way alone, but required always the aid 

 of an experienced coadjutor, willing to lose the greater portion of a night's 

 rest, often to be disappointed by failures resulting from the state of the 

 weather, and numberless impediments sufficient to damp the ardour of the 

 most enthusiastic. For some months Mr. Thornthwaite was so kind as to 

 continue his valuable aid, and several good positive pictures were obtained ; 

 but the difficulties we had to encounter were so great that it was at last resolved 

 to discontinue the experiments until such time as a driving motion could be 

 applied to the telescope. This was done early in 1857 §, since which period 

 I have unremittingly followed up the subject of celestial photography when- 

 ever my occupations and the state of the atmosphere have permitted me to 



* Astronomische Naclirichten, No. 1105, p. 1. 



f These pictures were exhibited in the early part of 1853 at the Royal Astronomical 

 Society. 



% Mr. Archer applied the solution of gun cotton (collodion) to photography in 1851, and 

 suggested pyrogallic acid for developing the latent image. 



§ Monthly Notices of the Roy. Ast. Soc, vol. xviii. p. 16. 



K 2 



