B. A. Gould—Diurnal Variation of Temperature. 99 
ate, which I suppose to belong to the same series as that of 
Grao Mogol. At other points, near the Sao Francisco river, 
diamonds appear in a region of a newer (though probably Pa- 
leozoic) conglomerate, and in the province of Purana, in a ° 
region of Devonian sandstone and conglomerate. In all these 
cases the diamond has most probably come out from its second- 
ary deposit—the conglomerate. Of course all rocks newer than 
the original formation and formed from its debris may contain 
the diamond. The original formation is most probably of 
Cambrian age. 
Art. X.—On the Algebraic Expression of the Diurnal Varia- 
tion of Temperature; by B. A. GOULD.* 
: * Translated from Vol. II. Chapter vi, of the “Anales de la Oficina Meteoro- 
gica Argentina,” by the author. 
