54 Obituary Notices of Fellows deceased. 



charge of the then new altazimuth instrument, one specially designed 

 by the Astronomer Royal for observation of the moon near to con- 

 junction -with the sun, before and after which epoch for a number of 

 days more or less observation on the meridian is impossible ; indeed, 

 with this instrument, observations in other parts of the lunation were 

 also frequently secured when the sky at meridian passage was cloudy. 



In 1851 Mr. Dunkin was deputed to proceed to Christiania to 

 observe the total solar eclipse of July 28. The weather on the occasion 

 was not altogether favourable ; he, however, saw three red promi- 

 nences, one of which being watched and showing no apparent change 

 of form gave him the impression of " some connection with the moon. " 

 He remarked, however, that the circumstances being rather difficult, he 

 was possibly deceived. It will be remembered that it was not until 

 the total eclipse of July 18, I860, that the red prominences were con- 

 clusively proved to be solar appendages. In 1854 Mr. Dunkin was 

 superintendent of a party of six observers organised by the Astronomer 

 Royal 10 make simultaneous pendulum observations at the surface and 

 at the bottom of the shaft of the Harton Colliery (near South Shields), 

 1260 feet deep, for determining, from the observed variation of 

 gravity, the mean density of the earth ; and in 1855 he was charged 

 with the setting up, in the Paris International Exhibition of that year, 

 of a large-sized model of the new Greenwich transit-circle. 



Before the establishment of the electric telegraph, the finding of 

 differences of longitude, with the exactness which in a scientific point 

 of view had become desirable, was a difficult problem. The method by 

 transmission of chronometers had given the best results, but it was an 

 operation troublesome and laborious and of necessity of restricted 

 application. On the connection of the English telegraphic system with 

 that of the Continent in 1851, by means of the Channel submarine 

 cable, astronomers eagerly looked forward to employment of the 

 telegraph for longitude purposes, and the Royal Observatory having 

 been placed in communication therewith, it devolved on Mr. Dunkin, 

 in conjunction with Sir Charles Todd (now Postmaster-General, South 

 Australia), to inaugurate the method in May, 1853, by an experi- 

 mental determination of the longitude of the Cambridge Observatory, 

 an operation that was entirely successful. It was at once seen that 

 the telegraph, wherever available, had placed in the hands of astrono- 

 mers a method that for convenience and accuracy surpassed all others 

 one that would become of great importance in geodetic work. It had 

 been intended as regards the Continent to apply the method first to a 

 determination of the longitude of Paris, but the illness and death of 

 Arago having retarded this operation, attention was given to Brussels, 

 the longitude of which was determined in the year 1853, being- 

 followed by that of Paris in 1854, in both of which operations 

 Mr. Dnnkin undertook a chief part, having for colleague in the latter 



