77 
Nearly a quarter of a century has elapsed since the moon 
was first photographed in America, and our friends on that 
side of the Atlantic have not been idle in the interval. To an 
American gentleman we are indebted for the best pictures of 
our satellite yet produced, and it is difficult to conceive that 
anything superior can ever be obtained ; and yet with the 
fact before us that Mr. De la Rue’s are better than any others 
taken in this country, so it may prove that even the marvel- 
lous pictures by Mr. Rutherford may be surpassed. 
Mr. Rutherford appears, from a paper in the American 
Journal of Science for May of the present year, to have begun 
his work in lunar photography in 1858 with an equatorial of 
eleven-and-a-quarter inches aperture, and fourteen feet focal 
length, and corrected in the usual way for the visual focus 
only. The actinic focus was found to be seven-tenths of an 
inch longer than the visual. The instrument gave pictures 
of the moon, and of the stars down to the fifth magnitude, 
satisfactory when compared with what had previously been 
done, but did not satisfy Mr. Rutherford, who, after trying to 
correct for the photographic ray by working with combina- 
tions of lenses inserted in the tube between the object glass 
and sensitive plate, commenced some experiments in 1861 
with a silvered mirror of thirteen inches diameter, which was 
mounted in a frame and strapped to the tube of the refractor. 
Mr. Rutherford enumerates several objections to the reflector 
for this kind of work, but admits the advantage of the coinci- 
dence of foci. The reflector was abandoned and a refractor 
specially constructed of the same size as the first one, and 
nearly of the same focal length, but corrected only for the 
chemical ray. This glass was completed in December last, 
but it was not until March 6th of the present year that a 
sufficiently clear atmosphere occurred, and on that night the 
negative was taken from which the prints were made, and 
'through the kindness of Dr. Roscoe I now have the pleasure 
of showing them to you. 
