Intelligence and Miscellaneous Articles. 227 



6'*61, and the year 1848 as presenting a maximum variation of 

 ll'-15. 



Sabine* (March, 1852), in searching for periodicallaws amongst 

 the mean effects of the larger magnetic disturbances, found a simul- 

 taneous period of increase and decrease both at Hobarton and To- 

 ronto, on opposite sides of the globe ; the minimum effect was in 

 1843, and the maximum effect in 1848, according therefore almost 

 exactly with Lament's observations at Munich. But, besides that, 

 he pointed out the extraordinary circumstance that this similar vari- 

 ation of the daily magnetic declination is the same in length of period 

 as that discovered by M. Schwabe for the solar spots ; and still more, 

 that the maxima and minima of these two most different phsenomena 

 coincide; for 1843 presents the least diurnal variation and the 

 smallest number of solar spots, and 1848 the largest magnetic 

 variation and the greatest number of solar observations. He has 

 also observed that the same period of increase and decrease exists 

 with the same epochs in the diurnal variation of the magnetic incli- 

 nation of the earth's magnetic force in both hemispheres. The 

 phsenomenon is general both as regards all the magnetic elements, 

 and in parts of the globe most distant from each other. 



Gautier appears to have been struck with the same coincidence, 

 but did not publish his idea until July 1852 f. Wolf of Berne, who 

 has sought far into the history of the sun spots, had the same 

 thought, publishing it first at the end of July or beginning of 

 August 1852 J. He endeavours to trace the general condition of 

 the spots from the year 1600, and concludes that the true length of 

 the period is 11*1 1 years. As it is impossible to conceive such a 

 coincidence in the length of the period and the time of the maxima 

 and minima of these two greatly differing phsenomena, without 

 believing in some relation of them to a common cause ; so, the 

 observation of such a coincidence at this moment ought to urge us 

 more than ever into an earnest and vigorous investigation of the 

 true and intimate nature of magnetism ; by means of which we now 

 have hopes of touching in a new direction, not merely this remark- 

 able force of the earth, but even the like powers of the sun itself. 



XXXVI. Intelligence and Miscellaneous Articles. . 



NOTICES OF THE SUPERPOSITION OF CERTAIN MINERALS IN 

 SOME MINING DISTRICTS OF GERMANY §. 



THE following interesting addition to our knowledge of the con- 

 ditions which accompany some of the rarer minerals, forms 

 an appendix to a translation of Mr. Henwood's inquiries on the same 

 subject in the mines of Cornwall and Devon ||. 



* Philosophical Transactions, 1852, p. 103. 



t Bibliotheque Universelle, 1852, xx. 189. 



X Proceedings of Natural Society of Berne, Nos. 245-247. 



§ Gangstudien oder Beitrdge zur Kenntniss der Erzgdnge, Herausgegeben 

 von B. Cotta, Dr. Ph. und Professor der Geognosie in Freiberg, vol. ii. 

 Heft 1. p. 120. 



II Lond. Edinb. and Dub. Phil. Mag. S. 3. vol. xxix. p. 359 (1846). 



