Projected, but never carried out. After Ramsden had to some extent
completed a 10-foot circle, he found such difficulties that he tried
a 9-foot, and this again he discarded for an 8-foot, which was
ultimately accomplished, though not entirely by himself.
Notwithstanding the contraction from the vast proportions originally
designed, the completed instrument must still be regarded as a
colossal piece of astronomical workmanship. Even at this day I do
not know that any other observatory can show a circle eight feet in
diameter graduated all round.
I think it is Professor Piazzi Smith who tells us how grateful he was
to find a large telescope he had ordered finished by the opticians on
the very day they had promised it. The day was perfectly correct; it
was only the year that was wrong. A somewhat remarkable experience
in this direction is chronicled by the early reports of the visitors
to Dunsink Observatory. I cannot find the date on which the great
circle was ordered from Ramsden, but it is fixed with sufficient
precision by an allusion in Ussher's paper to the Royal Irish
Academy, which shows that by the 13th June, 1785, the order had been
given, but that the abandonment of the 10-foot scale had not then
been contemplated. It was reasonable that the board should allow
Ramsden ample time for the completion of a work at once so elaborate
and so novel. It could not have been finished in a year, nor would
there have been much reason for complaint if the maker had found he
required two or even three years more.
Seven years gone, and still no telescope, was the condition in which
the Board found matters at their first visitation in 1792. They had,
however, assurances from Ramsden that the instrument would be
completed within the year; but, alas for such promises, another seven
years rolled on, and in 1799 the place for the great circle was still
vacant at Dunsink. Ramsden had fallen into bad health, and the Board
considerately directed that "inquiries should be made." Next year
there was still no progress, so the Board were roused to threaten
Ramsden with a suit at law; but the menace was never executed, for
the malady of the great optician grew worse, and he died that year.
Public-domain text, read in full here on John Shaqi.
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