in the Magnetic Forces of the Earth. 



357 



Whether the variations in the thickness of the stratum of daily 

 variations of temperature are sufficient to make the discrepancy 

 above noticed, entirely disappear, must be left for future conside- 

 ration. In fact, it will doubtless be necessary to have recourse to 

 direct observations before this question can be definitively settled, 

 and a complete explanation of all the details of the variations of 

 the vertical intensity made out with certainty. 



A farther investigation reveals the existence of olher small 

 discrepancies. These are exhibited to the eye in figs. 21 to 24, 



Curves of Mean Diurnal Variations of Vertical Force and Difference of Temperature. 



Fig. 21. 



Oa 



6k 



Fig. 22. 



Fig. 23. 



Fig. 24. 



Jan., Feb. and March, 1842. 



12a 



16a 





Oh 



April, May and June, 1841. 



July, Aug. and Sept., 1841. 



Oct., Nov. and Dec, 1841. 



0a 



^< «>Nt> Skiuks, Vol. Vlir, No. 24.— Nov., 1849. 



46 





