Thanking him for copies of books. People at Collingwood are gazing at the eclipse. Concerning the astatic needle.
Thanking him for copies of books. People at Collingwood are gazing at the eclipse. Concerning the astatic needle.
Sending his apologies for some errors he made in his calculations in his letter of 30 Nov.
Has made a trial of JH's lens but it was too large to be satisfactory. Regarding the 'graphoscope,' a new toy. Has been concerned with the manufacture of an improved form of opera glass. Present forms have many imperfections. Gives details of his own theories and sends one for JH's notice.
Thanks and a detailed description of the functioning of a pair of binoculars sent by JD to JH.
Thanks for his letter. Is glad the binoculars give a satisfactory performance, but regrets the width between the tubes does not suit JH's eyes. Will alter this and send a new pair later.
Moon not uniformly dark during last eclipse of sun. In 1858, Mr. Stuart saw same phenomenon, but JH, W. R. Dawes, and [James] Breen reported no such partial illumination. Suggests that this observation was due to refrangibility in medium, not to actual illumination of moon.
Sends an article from the Astronomische Nachrichten acknowledging the assistance of the B.A.A.S. to two Prussian scientists.
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