1878

The Report to the Board of Visitors has this paragraph:  “I continue to remark the approaching necessity for Library extension.  Without having absolutely decided on a site, I may suggest that I should wish to erect a brick building, about 50 feet by 20, consisting of two very low stories (or rather of one story with a gallery running round its walls), so low that books can be moved by hand without necessity for a ladder.—­In the month of December, 1877, the azimuthal error of the Transit Circle had increased to 10”.  A skilful workman, instructed by Mr Simms, easily reduced the error to about 2".5 (which would leave its mean error nearly 0), the western Y being moved to the north so far as to reduce the reading of the transit micrometer, when pointed to the south, from 35r.500 to 35r.000.  The level error was not sensibly affected.—­The Sidereal Standard Clock preserves a rate approaching to perfection, so long as it is left without disturbance of the galvanic-contact springs (touched by its pendulum), which transmit signals at every second of time to sympathetic clocks and the chronograph.  A readjustment of these springs usually disturbs the rate.—­To facilitate the observations of stars, a new working catalogue has been prepared, in which are included all stars down to the third magnitude, stars down to the fifth magnitude which have not been observed in the last two catalogues, and a list of 258 stars of about the sixth magnitude of which the places are required for the United States Coast Survey.  The whole number of stars in our new working list is about 2500.  It may be here mentioned that an extensive series of observations was made, during the autumn, of about 70 stars, at the request of Mr Gill, for comparison with Mars, Ariadne, and Melpomene.—­On Apr. 10th last, a very heavy fall of rain took place.  Between Apr. 10d. 5h. and Apr. 11d. 2h., 2.824 inch. was recorded, and 75 per cent. of this, or 2.12 inch., fell in the eight hours between 13-1/2h. and 21-1/2h.; and on May 7, 1 inch of rain fell in 50 minutes, of which 1/2 inch fell in 15 minutes.—­The supplementary compensation continues to be applied with success to Government chronometers which offer facilities for its introduction, and a marked improvement in the performance of chronometers returned after repair by the makers appears to have resulted from the increased attention now given to the compensation.  Of the 29 competitive chronometers, 25 have the supplementary compensation.”—­With regard to the reduction of the observations of the Transit of Venus:  After reference to the difficulties arising from the errors and the interpretation of the language used by some of the observers, the Report continues thus:  “Finally a Report was made to the Government on July 5th, giving as the mean result for Mean Solar Parallax 8".76; the results from ingress and from egress, however, differing to the extent of 0".11....  After further examination and consideration, the result for parallax has been