In the number of the ‘Monthly Notices’ for November 1862, will be found a very interesting account of the great equatorial telescope by the late Mr A Ross, which was shown at the 1851 Exhibition.
It is the property of Mr Grant, of Elchies, Morayshire; -
the focal length is 16 feet, and aperture 11 inches: the mounting on the German
plan, is by Ransome & May, of Ipswich. The declination and polar axes are
about 5 feet long and six inches in diameter; the circles are discs of gun
metal, 30 inches in diameter and one inch thick. One portion of the stand
consists of 1 tons of iron, the greatest quantity ever cast into a single piece
for any astronomical instrument.
The climate of Great Britain very unfavourable to the
performance of large telescopes of this character: in the ‘Monthly Notices’ of
March 10th 1854, Mr Grant gives two drawings of Mars, one which, taken with a
five feet telescope in India, he says is “actually a little world”, - that
taken with the great telescope described above is not nearly so distinct in
details,- and he adds, “ I doubt whether the large glass would show it equally
well, even were the weather favourable”.
Professor C P Smyth, who made several observations with the
Elchies Equatorial last September says, “there were only two occasions during
the week when I had the good fortune to witness, for a few minutes each time, a
cessation of those atmospheric disturbances on the which the definition of
stars seen in a good telescope so greatly depends.” This is but proof, that an
instrument of moderate size is more generally useful in this country than one
of excessive proportions.
www.theramblingastronomer.co.uk
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