TERRESTRIAL MAGNETISM. 41 



tories at St. Helena, the Cape of Good Hope, and Van Die- 

 men's Land ; the two former being under the respective direc- 

 tion of Lieutenants Riddell, Lefroy and Wihnot, of the Royal 

 Artillery ; the latter it is contemplated to place under the direc- 

 tion of one of the naval officers attached to the expedition, vi^ho 

 will be left in charge of it. 



The observatory at Montreal, in Canada, will be placed under 

 the direction of Lieutenant Riddell of the Royal Artillery, who 

 will proceed immediately to his station*. 



As regards the proposed observatory at Ceylon, it has ap- 

 peared to your Committee, on mature consideration, that 

 Madras will be in many respects a preferable point, and they 

 therefore have not insisted on Ceylon in their representations 

 to Government, it being understood by them to be the intention 

 of the Royal Society to recommend to the Honourable Court of 

 Directors of the East India Company^ to order the establish- 

 ment of observatories in every respect similar, at that and two 

 other stations in British India. This recommendation, your 

 Committee understand, has been accordingly made, and at 

 once acceded to in the most liberal manner, and the instru- 

 ments immediately ordered ; while Major Jervis, the provisional 

 Surveyor-General of India, has recently visited Dublin for the 

 purpose of familiarizing himself with the practical details and 

 manipulations of the observations and instruments as adopted 

 in the magnetical observatory of Dublin. Messrs. Riddell, 

 Wilmot, and Lefroy, have also availed themselves of the same 

 opportunity ; and, by the subsequent erection at Woolwich of 

 a set of the magnetic instruments, every facility has been af- 

 forded to the officers of the naval expedition for becoming ac- 

 quainted with the processes. 



The staff of each observatory will consist of the officer in 

 charge, three non-commissioned officers, and two gunners, by 

 which it is expected that the observations will be continued 

 throughout the 24 hours ; i. e. at every second hour throughout 

 the day and night. 



Each observatory is supplied with a very complete set of me- 

 teorological instruments, by which not only will the requisite 

 data be afforded for the due correction and reduction of the 

 magnetic observations, and for tracing the influence, if any, of 

 meteorological changes on the magnetic elements, but a most 

 valuable and complete series of meteorological observations will 

 be procured at every station, made with compared instruments, 

 and on a perfectly uniform system. 



* Montreal has been subsequent!}' cbaiiged for Toronto. 



