1865.1 IQI [Chase. 



The recent experiments of Marcus, showina: the direct conversion 

 of heat into electricity (see London Cheraical News, No. 286; Jour- 

 nal of the Franklin Institute, No. 478), the well-known atmospheric 

 daily cycles, with two maxima and two minima of electrical inten- 

 sity,* and the tendency of the disturbance-variations of declination, 

 inclination, and total force, to fluctuations which follow the solar-tidal 

 and barometric-tidal hours,f are all noteworthy in this connection. 



In the regions of variable winds, it can hardly be supposed that 

 the correspondence between changes of wind and of declination 

 should be so marked as in the torrid zone. I find, however, upon 

 tabulating about two thousand of the Toronto Observations, that 

 there are some indications of a similar character to those in the St. 

 Helena Table ; but they are, comparatively, so slight, that another 

 form of comparison has given results which are more satisfactory to 

 my own mind. J 



According to my several hypotheses, the magnetic impulses are 

 transmitted with a velocity analogous to that of light, and the posi- 

 tion of the needle at any moment is dependent upon the combined 

 action of local and cosmical forces, the former producing continual 

 agitations of short period, and the latter largely preponderating in 

 the daily means. On the other hand, the barometric and other 

 atmospheric changes, in consequence of greater inertia, are more 

 obedient to cumulative influences that have a limited local origin, 

 and less affected by sudden violent disturbances. It seems reason- 

 able, therefore, to suppose that the oscillations about the mean mag- 

 netic values should differ, in duration and in other respects, from 

 those about the thermal and barometric means. If their mutual 

 relations are much obscured in consequence of this difference, any 

 lingering evidences of inter-dependence that we may find may be 

 entitled to great weight. 



* For some recent interesting observations upon atmospheric electricity, see 

 communications of Dr. A. Wislizenus in the Transactions of the Academy of Sci- 

 ences, St. Louis. 



t The long series of observations at Toronto show this correspondence in a 

 very striking manner. See Gen. Sabine's Report, vol. iii, p. 63, table Ivi. 



I M. Kaemtz (Meteorology, Walker's translation, p. 451) states that "the dip 

 depends, like the height of the barometer, on the direction of the wind and on 

 temperature." This is the earliest intimation I have yet discovered, which can 

 be possibly construed as either implying or tending to demonstrate a direct cor- 

 relation between weight and magnetism. The resemblance between the curves 

 of wind-force and magnetic vertical force, would naturally lead one to look to the 

 dip rather than to the declination, for the most striking evidence of the magnetic 

 effects of direction of the wind. 



