History of the Kew Observatory. 



57 



secured, contiguous to the Observatory. Welsh's standard barometer 

 dates from 1855, and the introduction of gas to the Observatory from 

 the next year. In the same year Mr. Balfour Stewart was engaged 

 as Assistant, but he only remained for a brief period in that capacity, 

 for in 1857 he was succeeded by Mr. Charles Chambers. 



In 1856 Mr. Beckley's modification of Robinson's anemometer 

 was submitted to the Committee, and also a series of monthly 

 determinations of dip and horizontal force was commenced with 

 instruments provided by General Sabine from his Department at 

 Woolwich. 



The next important event to be chronicled is that the following 

 Memorandum relative to the re-establishment of self-recording 

 magnetic instruments at the Kew Observatory was submitted to 

 the Committee by General Sabine on July 22, 1856 : — 



" 1. The decennial period in the solar magnetic variations, and its 

 coincidence with a similar period in the frequency and amount of 

 the solar spots, appear to be highly deserving of attention in an 

 Observatory established, as Kew is, for physical researches. 



" 2. There is reason to suppose that the permanency and regularity 

 in the occurrence of the decennial period in the magnetic variations, 

 and its coincidence with the periodic variation of the solar spots, 

 might be effectually and satisfactorily tested by observations of both 

 classes of phenomena at the alternate periods of maximum and 

 minimum, say, for example, in 1857 and 1858 as the anticipated 

 period of maximum, and in 1863 and 1864 as the anticipated period 

 of minimum, and so forth. 



" 3. The apparatus constructing under the superintendence of 

 Mr. de la Rue will, it is hoped, fully meet the requirements of the 

 research in respect of the solar spots. 



"4. Since the time when the magnetic self-recording instruments 

 belonging to the Kew Observatory were constructed under the direc- 

 tion of Mr. Ronalds, very considerable improvements have been made 

 in the art of photography, and the six months' trial which was made 

 by Mr. Welsh of Mr. Ronalds's instruments has led in several other 

 respects to suggestions for improvements which could not but be 

 expected to be required in instruments of so novel a kind, while at 

 the same time the six months' trial referred to has placed beyond 

 doubt the sufficiency of a properly conducted research by means of 

 self-recording instruments, for the examination of the solar magnetic 

 variations." 



The Committee authorized Mr. Welsh to proceed with the construc- 

 tion of the instruments, which were completed at an expense not 

 exceeding 250L, derived from the Government Grant Fund, the 

 instruments remaining at Kew at the disposition of the Council of 

 the Royal Society. 



