Royal Society. 63 



the one displayed by the original discovery of magnetism itself, 

 in the connection that it bears to electricity and in the induc- 

 tion from rotary motion. It was important, however, that 

 experiments should be repeated in different places, and espe- 

 cially in those which are most difficult of access, but situated 

 near to the magnetic pole. 



Lieutenant Henry Foster, well known to this Society by 

 the cooperation he afforded to Captain Basil Hall in deter- 

 mining the number of vibrations made by an invariable pen- 

 dulum near the equator, and at several other stations ; having 

 shared in the dangers of Captain Parry's second voyage, 

 eagerly seized the opportunity afforded by a winter residence 

 at Port Bowen, on the eastern side of Prince Regent's Inlet, in 

 lat. 73° 14/, to ascertain the rate of an invariable pendulum, 

 to conduct an elaborate course of experiments on magnet- 

 ism ; and in addition to these, observations on refraction. 



One is utterly astonished at the magnitude of these labours, 

 and at the accuracy and care with which they were conducted, 

 (as is manifest from internal evidence,) in a situation where 

 comfort and ease were unattainable, and where peculiar dif- 

 ficulties presented themselves at every step. It is impossible 

 for me to give an abstract of Mr. Foster's most ample and 

 detailed communication : I must refer every scientific inquirer 

 to the paper itself. Among its important contents are : — The 

 amount and times of daily variation attributable of course to 

 the sun, but including in one series the action apparently 

 caused by the moon. — The line on which a needle being di- 

 rected the daily variation ceases. — A refutation of the supposed 

 connection between tremors of the needle and aurora borealis. 

 — The amount and times of daily variation in the dip ; with 

 a deduction from thence, according to the known law of the 

 cosines, to the periodical change in horizontal intensity. — And 

 a legitimate conclusion from all these facts, that the magnetic 

 axis of the earth may probably describe a small curve, com- 

 pounded of circles attributable to the sun and moon, of two 

 or three minutes' radius round its mean place, which will solve 

 the change of dip, of diurnal variation and of horizontal inten- 

 sity ; and may account for the secular variation in a manner 

 similar to that which explains the precession of the equinox. 



The Royal Society are of opinion that they do no more 

 than strict justice, in awarding their Copley medal to the au- 

 thor of these observations and deductions ; and not without a 

 hope that by so doing, public attention may be more strongly 

 drawn towards an officer possessing such abilities, energies, 

 and preseverance # . 



* Never were expectations more speedily or more amply gratified ; tot 



on 



