1864. ] 
(o)88l-~) 
NOTES AND CORRESPONDENCE. 
Sinverrp Guass TELESCOPES AND CELESTIAL PHoToGRAPHY IN AMERICA. 
By Professor Henry Draper, M.D., New York University. 
New York, Feb, 2, 1864. 
THE first photographs of the moon 
were taken in 1840 by my father, 
Professor John W. Draper, M.D., 
who published notices of them in 
his quarto work, ‘On the Forces 
that Organize Plants,’ and in the 
‘ Philosophical Magazine.’ The speci- 
mens were about an inch in diameter, 
and were presented to the Lyceum 
of Natural History of New York. 
They were made by means of a lens 
of five inches aperture, furnished 
with an eye-piece to increase the 
magnifying power, and mounted on 
a polar axis driven by a clock. At 
that time it was generally supposed 
that the moon’s light contained no 
actinic rays, and was entirely with- 
out effect on the sensitive silver com- 
pounds used in daguerreotyping. 
In 1850, Mr. Bond made use of the 
Cambridge (Massachusetts) refrac- 
tor of 15 inches’ aperture, to produce 
daguerreotype impressions of our 
satellite, the sensitive plate being 
placed at the focus of the object- 
glass, without the intervention of 
an eyepiece. Pictures two inches 
in diameter were thus produced, 
and, subsequently, some of the same 
size were made on glass, and 
mounted stereoscopically. Mr. Bond 
also made a series of experiments 
to determine whether photography 
could be advantageously applied to 
the measurement of double stars, 
and concluded that the results were 
as reliable as those derived from the 
micrometer.* 
Soon after, Mr. Warren De La 
Rue, of Cranford, near London, un- 
dertook by the aid of a 13-inch 
speculum, ground and polished by 
himself, to procure a series of pho- 
tographs of the moon and other 
celestial objects. The excellent re- 
* «Astron. Nach,’ No. 1129. 
sults that he has obtained, together 
with those of Professor Phillips, Mr. 
Hartnup, Mr.Crookes, Father Secchi, 
and other physicists, are doubtless 
familiar to all scientific men, having 
been published in the form of a re- 
port to the British Association in 
1859. No detailed description of 
them is necessary, therefore, in this 
place. 
In 1857 Mr. Lewis M. Rutherfurd, 
of New York, erected an equatorial 
refractor of 11 inches’ aperture, the 
object-glass of which he had himself 
corrected, and has taken a large 
number of lunar photographs with 
it. They have generally borne to 
be magnified to five inches, and he 
is now engaged in perfecting a cor- 
recting lens that will allow still 
greater enlargement to be used. 
The moon, as seen by the naked 
eye, is about one-tenth of an inch in 
diameter,although persons generally 
estimate it at 10 inches. That the 
first statement is true is easily 
proved either by taking a photo- 
graph with a lens of 10 inches’ 
focal length, or more convincingly 
by holding up between the moon 
and the eye a little dise one-tenth 
of an inch across, at the near- 
est distance of distinct vision (10 
inches). A picture of the moon 
of the size commonly attributed to 
her requires to be made under a 
power of 100 times. 
In 1857 I visited Lord Rosse’s 
great reflecting telescopes at Par- 
sonstown, and had an opportunity 
of not only seeing the grinding and 
polishing operation by which they 
were produced, but also of obsery- 
ing some stars through the six-foot 
instrument. On returning home in 
1858 it was determined to construct 
a large instrument by similar means, 
and devote it especially to celestial 
photography. The speculum was of 
