Sciences of Meteorology and Terrestrial Magaetian. 135 



the correspondence is truly remarkable. To put this striking con- 

 nection almost beyond a doubt, Gen. Sabine found that the viean 

 diurnal variation exhibited a change in different years, and had a maxi- 

 mum and minimum correspondence with the solar spots ; and that 

 1843 and 1848 were two such periods. On calculating backwards 

 for previous epochs of the spots, there was found an exact cor- 

 respondence. 



The moon, also, has been recognized, first by M. Kreil, director of 

 the Austrian observatories, and since by Gen. Sabine, as slightly influ- 

 encing the variations of the magnetic elements ; but here there is no 

 trace whatever of a decennial period. 



These late results are extremely striking, and open up to us new views 

 regarding the great cosmical phenomena, as well those relating to the 

 earth and its magnetism, as to the constitution and action of the great 

 photosphere of the sun himself. —They seem to point to vast secular 

 changes in the magnetism of the sun ; and, in connection with the highly 

 probable existence of a magnetic medium, pervading all space, suggest 

 new relations among the imponderable agents, — heat, light, electricity, 

 and magnetism, which play so important a part in the economy of the 

 universe. 



January 13, 1858. — The Pcesident in the Chair. 



Mr. William Gilmour was elected a member. 



Mr. Thomas Nicolson, Writer, 20 Buchanan Street, was proposed as 

 a member by Mr. James Young, Mr. John Ure, and Mr. Keddie. 



Mr. Edmund Hunt gave further illustrations of his paper " On certain 

 Phenomena connected with Rotatory Motion." 



Professor William Thomson showed, by a series of experiments, the 

 different conductivity of various samples of Copper Wire. The inquiry 

 was suggested by circumstances which arose in connection with the con- 

 struction of the Atlantic Telegraph Cable ; and the results which have 

 come out are very surprising, and such as no one had anticipated. The 

 power of transmitting an electric current differed extremely in different 

 specimens of wire, though these were manufactured in the same way 

 and at the same establishment. Chemical analysis showed no difference 

 in composition ; and that the state of crystalline aggregation had no 

 effect, was proved by the circumstance that stretching, twisting, or 

 compression in no way affected the conductivity. The cause of the 

 difference must be held as still entirely unexplained; yet so great is this 

 diversity of conducting power, that the use of the best conducting wire 



Vol. IV.— No. 1. 2 b 



