Chapter 24

CHAPTER XXIV

THE TELESCOPE OF THE ROCKY MOUNTAINS

On the 20th of October in the preceding year, after the close of
the subscription, the president of the Gun Club had credited the
Observatory of Cambridge with the necessary sums for the
construction of a gigantic optical instrument. This instrument
was designed for the purpose of rendering visible on the surface
of the moon any object exceeding nine feet in diameter.

At the period when the Gun Club essayed their great experiment,
such instruments had reached a high degree of perfection,
and produced some magnificent results. Two telescopes in
particular, at this time, were possessed of remarkable power
and of gigantic dimensions. The first, constructed by Herschel,
was thirty-six feet in length, and had an object-glass of four
feet six inches; it possessed a magnifying power of 6,000.
The second was raised in Ireland, in Parsonstown Park, and belongs
to Lord Rosse. The length of this tube is forty-eight feet, and
the diameter of its object-glass six feet; it magnifies 6,400
times, and required an immense erection of brick work and
masonry for the purpose of working it, its weight being twelve
and a half tons.

Still, despite these colossal dimensions, the actual
enlargements scarcely exceeded 6,000 times in round numbers;
consequently, the moon was brought within no nearer an apparent
distance than thirty-nine miles; and objects of less than sixty
feet in diameter, unless they were of very considerable length,
were still imperceptible.

In the present case, dealing with a projectile nine feet in
diameter and fifteen feet long, it became necessary to bring the
moon within an apparent distance of five miles at most; and for
that purpose to establish a magnifying power of 48,000 times.

Such was the question proposed to the Observatory of Cambridge,
There was no lack of funds; the difficulty was purely one
of construction.

After considerable discussion as to the best form and principle
of the proposed instrument the work was finally commenced.
According to the calculations of the Observatory of Cambridge,
the tube of the new reflector would require to be 280 feet in
length, and the object-glass sixteen feet in diameter.
Colossal as these dimensions may appear, they were diminutive
in comparison with the 10,000 foot telescope proposed by the
astronomer Hooke only a few years ago!

Regarding the choice of locality, that matter was
promptly determined. The object was to select some lofty
mountain, and there are not many of these in the United States.
In fact there are but two chains of moderate elevation, between
which runs the magnificent Mississippi, the "king of rivers"
as these