Autobiography of Sir George Biddell AiryAiry, George Biddell
Science
Autobiography of Sir George Biddell Airy
Airy, George Biddell
Airy, George Biddell, 1801-1892; Astronomers -- Great Britain -- Biography; Autobiographies; Royal Greenwich Observatory
"On May 3rd 1853 I issued an address to the individual Members of the
Board of Visitors, proposing the extension of the Lunar Reductions
from 1830. From this it appears that 'Through the whole period (from
1830 to 1853), the places of the Moon, deduced from the observations,
are compared with the places computed in the Nautical Almanac: that
is, with Burckhardt's tables, which have been used for many years in
computing the places of the Nautical Almanac.......Very lately,
however, Mr Adams has shewn that Burckhardt's Parallax is erroneous in
formula and is numerically incorrect, sometimes to the amount of seven
seconds. In consequence of this, every reduction of the Observations
of the Moon, from 1830 to the present time, is sensibly erroneous. And
the error is of such a nature that it is not easy, in general, to
introduce its correction by any simple process.... The number of
observations to the end of 1851 (after which time the parallax will be
corrected in the current reductions) is about 2560. An expense
approaching to _£400_ might be incurred in their reduction.'
Subsequently I made application to the Admiralty, and the _£400_ was
granted on Dec. 12th.--In the Report to the Visitors it is stated that
with regard to the Transit Circle, changes are under contemplation in
its reflection-apparatus: one of these changes relates to the material
of the trough. 'Several years ago, when I was at Hamburgh, my revered
friend Prof. Schumacher exhibited to me the pacifying effect of a
copper dish whose surface had been previously amalgamated with
quicksilver.......The Rev. Charles Pritchard has lately given much
attention to this curious property of the metals, and has brought the
practical operation of amalgamation to great perfection. Still it is
not without difficulty, on account of a singular crystallization of
the amalgam.'--With regard to the Chronograph, the Report states: 'The
Barrel Apparatus for the American method of observing transits is not
yet brought into use.... I have, however, brought it to such a state
that I am beginning to try whether the Barrel moves with sufficient
uniformity to be itself used as the Transit Clock. This, if perfectly
secured, would be a very great convenience, but I am not very sanguine
on that point.'--A change had been made in the Electrometer-apparatus:
'A wire for the collection of atmospheric electricity is now stretched
from a chimney on the north-west angle of the leads of the Octagon
Room to the Electrometer pole.... There appears to be no doubt that a
greater amount of electricity is collected by this apparatus than by
that formerly in use.'--As regards the Magnetical Observations: 'The
Visitors at their last Meeting, expressed a wish that some attempt
should be made to proceed further in the reduction or digest of the
magnetical results, if any satisfactory plan could be devised. I
cannot say that I have yet satisfied myself on the propriety of any
special plan that I have examined....
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