1866. | De la Rue and Celestial Photography. 361 
merely of chemical (actinic) intensity, as would be the case if it 
were an instance of loss by the absorption in the solar atmosphere ; 
but there is evidence of a changed condition, such as is shown 
by the protected bands observed under the yellow and the red 
rays, where luminous and calorific power attain their maximum 
influence. On this pomt we have yet a few more words to say. 
Professor Bond, of Cambridge, with Messrs. Whipple and 
Black, of Boston, in the United States, were the first to make a 
photographic picture of any celestial body. This was an image 
of the moon, obtained upon a Daguerreotype plate, which had been 
placed in the focus of the refracting telescope of the Harvard 
Observatory. In 1851, some of these Daguerreotypes of our satel- 
lite were in the American department of the Great Exhibition. 
In 1852, Mr. Warren De la Rue obtained positive lunar photo- 
graphs, in from ten to thirty seconds, on a collodion film, by means 
of an equatorially-mounted reflecting telescope of thirteen-inch 
aperture and ten-teet focal length. At this time Mr. De la Rue 
had not applied any mechanical driving motion to his telescope. 
He was therefore constrained to contrive some other means of 
following the moon’s apparent motion. This he 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 tele- 
scope, but subsequently by means of a sliding frame fixed on the 
eye-piece holder, the motion of the slide being adjustable to suit 
the apparent motion of the moon. As the pictorial image of the 
moon could be seen through the collodion film, and could be 
rendered immovable 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 to 
the back of a little camera-box which held the plate, this was 
effective. 
Excellent results were obtained under the disadvantages of the 
want of an automatic drivmg motion, which proved how perfectly 
the hand may be made to obey the eye. Mr. Warren De la Rue 
was admirably aided in his earliest experiments by Mr. Thornthwaite, 
since it was found impossible to work without the assistance of 
an experienced coadjutor. 
In 1853, Professor John Phillips communicated to the Hull 
meeting of the British Association the results of his experience in 
Lunar Photography, and he then exhibited some excellent pictures 
of our satellite. Mr. Hartnup, of Liverpool, aided by Mr. Crooke 
and other photographers, took some good pictures of the moon in 
1854. Father Secchi, at Rome, Mr. Fry, i Mr. Howell’s observ- 
atory at Brighton, and Mr. Huggins, now so well known by his 
application of spectrum analysis to the stars, nebule, and comets, 
also produced lunar pictures. A great extension of pha Photo- 
B 
