Report to the Secretary of the Navy on Recent Improvements in Astronomical Instruments - Couverture rigide
Présentation de l'éditeur
January 29, 1334 t Ivisited certain of cpe during the past :ting the most recent hods of observation. nrt upon the knowl not arranged with with respect to the sch instrument beln8 gathered at various nformation was gath Beneva, Vienna, Berrkshop of the Messrsed the opportunity Âf Âtory, and of discussreat 30-inch refractor, by the Messrs. Olarlr the very cordial reof the various obsere alforded me for the d. In every case thecal an examination of at exhaustive discusmight have been exat my disposal it WBB make the tests which hall therefore conllne important to persons to design or purchase ed that to which most 7ntly completed for the lrubb, esq., of Dublin. se at the present time, IMPROVEMENTS IN ASTRONOMICAL INSTRUMENTS. 3being of one inch greater aperture than that of the Naval Observatory at Washington. The contract was made with Mr. Grubb in 1875, but, owing to ditllculties in procuring glass disks of the necessary size and purity, it was not completed until 1881. Further delay occurred in mounting, so that it was barely ready for active work at the time of my visit in A pril last. I made as careful and critical an examination of its working as was possible during the unfavorable weather which prevalled at that time at Vienna. My examination was principally in the nature of a comparison of its working with that of the Washington telescope. General style of mounting. -I nits main features the telescope is mounted on the same fundamental plan as that at Washington, each being on the German plan, with the German system of counterpoises and with a steel tube. In both, the rapid motion in declination is by means of a rope attached to the two ends of the tube; that in right ascension by a system of wheel-work. In both, the clock-work is in the pier below the instrument. The leading points of difference are, that the mounting of the Vienna telescope is much
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