1853

“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 L400 might be incurred in their reduction.’  Subsequently I made application to the Admiralty, and the L400 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....