PHYSICS OF THE GLOBE. 77 



and back again. In this explanation, however, Blanford 

 makes no use of the important laws of dynamics, according 

 to which the distribution of density (as depending on tem- 

 perature and moisture and latitude) definitely fixes the law 

 according to which the pressure must vary with the loca- 

 tion and the time. 



Professor Balfour Stewart, in some remarks on Mr. J. A. 

 Broun's discoveries, maintains that the electrical state of the 

 atmosphere may very plausibly be introduced to explain the 

 general disturbances or tides in the barometric pressure. 



Mr. Buchan has received from the Royal Society of Edin- 

 burgh the Macdougall-Brisbane gold medal for his paper on 

 the diurnal oscillations of the barometer. 



PRECIPITATION, CLOUDS, ETC. 



The question as to the existence of fog vesicles is reviewed 

 by Von Obermayer, who concludes that the assumption of 

 fine drops of water suffices to explain all phenomena that 

 have hitherto been ascribed to vesicles, and that the forma- 

 tion of fine drops is much more plausible on account of its 

 simplicity. Angus Smith has observed in Iceland fog par- 

 ticles of ^-i-Q- inch diameter, or ten times that of the ves- 

 icles observed by Saussure. 



Malloch has attempted to determine the altitude of the 

 clouds by the comparison of photographic pictures taken 

 simultaneously at two stations. This method, which was 

 earnestly advocated by the author in 1871, seems calculated 

 to give better results than any other, although demanding 

 special precautions. Malloch estimates his extreme errors 

 at three per cent, of the whole. He found the cirri of July 

 and August to be at an altitude of from 22,000 to 27,000 

 feet ; large cumuli (the bases) at 6000 or 7000 feet ; rain- 

 clouds appeared at all altitudes up to 4000 feet. 



K. Antolik, of Hungary, calls attention to the remarkable 

 phenomena shown when frictional electricity is allowed to 

 act upon a quiescent cloud of tobacco smoke, which has 

 flowed down upon and spread over a horizontal table. In 

 this cloud he is able to reproduce the appearance of the 

 most delicate cirro-cumuli, the cumuli, the mares'-tails, and 

 other modifications of the forms of clouds. He would by 

 these phenomena endeavor to explain the mode of forma- 



