ASTRONOMY IN AMERICA. 
357 
aperture, which is now the chief equatorial of the observatory. 
America is fortunate in possessing in Alvan Clark the greatest 
living master of the art of constructing large object-glasses of 
good definition. He had already constructed a telescope 18 
inches in aperture for the observatory at Chicago ; but by the 
contract negotiated with him in August 1870 by Professor 
Newcomb, he was called on to achieve a far more difficult task 
in the construction of a telescope of 26 inches clear aperture. 
He has successfully accomplished this task, and the telescope 
has already obtained good results under Newcomb’s skilful 
management. The most important of these is an extensive 
series of observations of the satellites of Uranus and Neptune, 
made with a view of determining the elements of their orbits 
and the masses of the planets round which they circle. The 
observation of the two Uranian satellites, Ariel and Umbriel, dis- 
covered by Lassell, and of the Neptunian satellite also discovered 
by him, must be regarded, on account of the extreme difficulty of 
observing these bodies, as a very valuable contribution to 
astronomy. It is pleasant to notice that Newcomb has been 
able most thoroughly to confirm the accuracy of Lassell’s work 
in Malta, the mean motions of Ariel and Umbriel deduced from 
the Malta observations being so accurate that, says Newcomb, 
“they will probably suffice for the identification of those objects 
during several centuries.” Although no systematic search has 
been made for new satellites of Uranus, yet enough has been 
done to show, “ with considerable certainty,” that at least the 
outer satellites supposed to have been seen by Sir W. Herschel 
66 can have had no real existence ” (as satellites, that is to say). 
Before passing to the brief consideration of the work accom- 
plished in some of the other American observatories, we must 
fully admit the justice of the remarks made by Professor Nourse 
in closing his memoir relating to it. “ The position now 
accorded to it,” he says, “ by the free tributes of scientific men 
in the Old W orld as well as at home, is not without honour to 
our country ; and this notwithstanding the comparatively recent 
founding of the institution, and the as yet limited appropria- 
tions sustaining it. It may, therefore, justly claim a yet more 
generous support ; and the pledge may be safely made that if 
thus supported and efficiently directed, it will make returns 
yet more gratifying to national pride, and (which is a matter 
infinitely more important) advancing the highest aims of 
scientific research. What shall be its future records of success 
must remain with the support extended by the government and 
the fidelity of those who are entrusted with its administration.” 
The actual commencement of astronomical observation in 
America belongs to a much earlier period than that at which 
the Washington Observatory was erected. The first telescope 
