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Page 41
It was in the year 1887 that the Lick Observatory on Mount Hamilton,
of the Coast Range in Southern California, was completed. The lens of
this instrument is thirty-six inches in diameter. Nor will the reader
without reflection readily realize the enormous stride which was made
in telescopy when the makers advanced from the twenty-seven-inch to
the thirty-six-inch objective. Lenses are to each other in their power
of collecting light and penetrating apace as the squares of their
diameters, and in the extent of space explored as the cubes of their
diameters.
The objective of the Pulkova instrument is to that of the Lick
Observatory as 3 is to 4. The squares are as 9 is to 16, and the cubes
are as 27 is to 64. This signifies that the depth of space penetrated
by the Lick instrument is to that of its predecessor as 16 is to 9,
and that the astronomical sphere resolved by the former is to the
sphere resolved by the latter as 64 is to 27--that is, the Lick
instrument at one bound revealed a universe _more than twice as great_
as all that was known before! The human mind at this one bound found
opportunity to explore and to know a sidereal sphere more than twice
as extensive as had ever been previously penetrated by the gaze of
man.
Nor is this all. The ambition of American astronomers and American
philanthropists has not been content with even the prodigious
achievement of the Lick telescope. In recent years an observatory has
been projected in connection with the University of Chicago, which has
come almost to completion, and which will bear by far the largest
telescopic instrument in the world. The site selected for the
observatory is seventy-five miles from the city, on the northern shore
of Lake Geneva. There is a high ground here, rising sufficiently into
a clear atmosphere, nearly two hundred feet above the level of the
lake.
The observatory and the great telescope which constitutes its central
fact are to bear the name of the donor, Mr. Yerkes, of Chicago, who
has contributed the means for rearing this magnificent adjunct of the
University. The enterprise contemplated from the first the
construction of the most powerful telescope ever known. The
manufacture of the objective, upon which everything depends, was
assigned to Mr. Alvan G. Clark, of Cambridgeport, Massachusetts, who
is the only living representative of the old firm of Alvan Clark &
Sons.
Alvan G. Clark has inherited much of the genius of his father, though
it is said that in making the lens of the Lick Observatory the father
had to be called from his retirement to superintend personally some of
the more delicate parts of the finishing before which task his sons
had quailed. But the younger Clark readily agreed to make the Geneva
lens, under the order of Yerkes, and to produce a perfect objective
_forty inches in diameter_! This important work, so critical--almost
impossible--has been successfully accomplished.
The making and the mounting of the Yerkes telescope have been assigned
to Warner & Swasey, of Cleveland, Ohio, who are recognized as the best
telescope builders in America. The great observatory is approaching
completion. The instrument itself has been finished, examined,
accepted by a committee of experts, and declared to fulfill all of the
conditions of the agreement between the founder and the makers. Thus,
just north of the boundary line between Illinois and Wisconsin, the
greatest telescope of the world has been lifted to its dome and
pointed to the heavens.
The formal opening of the observatory is promised for the summer
months of 1896. The human mind by this agency has made another stride
into the depths of infinite space. Another universe is presently to be
penetrated and revealed. A hollow sphere of space outside of the
sphere already known is to be added to the already unthinkable
universe which we inhabit. Every part of the immense observatory and
of the telescope is of American production, with the single important
exception of the cast glass disc from which the two principal lenses,
the one double convex and the other plano-concave, are produced. These
were cast by Mantois, of Paris, whose superiority to the American
manufacturers of optical glass is recognized.
It is estimated that the Yerkes telescope will gather three times as
much light as the twenty-three-inch instrument of the Princeton
Observatory. It surpasses in the same respect the twenty-six-inch
telescope at the National Observatory in the ratio of two and
three-eighths to one. It is in the same particular one and four-fifth
times as powerful as the instrument of the Royal Russian Observatory
at Pulkova; and it surpasses the great Lick instrument by twenty-three
per cent.
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