B. TERRESTRIAL PHYSICS AND METEOROLOGY. 93 



The diminution varied from 0.045 to 0.024 of a foot per day. 

 The fluctuation of the rainfall year by year is quite large, 

 and so distributed that on the average sixteen periods of 

 great and little rainfall may be anticipated in every hundred 

 years. Since it has been, during the past few years, suggested 

 that the periods of fluctuation of the spots on the sun's disk 

 bear a relation to the fluctuations of rainfall, similar to those 

 which have been demonstrated in the case of terrestrial mao;- 

 netism, Mr. Binnie has sought to test the truth of this state- 

 ment by making a comparison between the fluctuations of 

 the rainfall at fourteen places and the solar-spot periods from 

 Schawbe's observations ; but no satisfactory result or accu- 

 rate deductions could be drawn from this test. Journal In- 

 stitution Civil Engineers. 



ON THE THEORY OF HAIL. 



Renou having proposed some objections to the theory of 

 the formation of hail which Faye has recently had occasion 

 to develop in connection with his theories relating to storms, 

 he has replied to Renou, to the efiect that hailstones are, in 

 general, formed by successive accretions of coatings of ice, 

 which latter are due to the cooling of the air to a point be- 

 low its dew-point and below the freezing-point. Admitting 

 that the nucleus may have a very low temperature, the same, 

 viz., as that of cirrus clouds, it is easy to see that in virtue 

 of this low temperature it will congeal around it a thin layer 

 of transparent ice, and that, if the physical and mechanical 

 conditions where it is remain the same, the hailstone will be 

 kept at a temperature in the neighborhood of the freezing- 

 point, and will, by the consolidation of the thin envelope and 

 evolution of heat, no longer continue to grow, but need again 

 to be cooled. The thickness of the shell thus formed after 

 any one exposure to the moist air can not exceed one twelfth 

 of the diameter of the nucleus. 6 B^ LXXXI., 513. 



RAINFALL OF BOHEMIA. 



Among the recent monographs upon meteorological spe- 

 cialties, we notice a memoir by Professor Studnicke, read 

 before the Bohemian Scientific Association of Prague, on the 

 rainfall of Bohemia. The climatology of Bohemia has been 

 most exhaustively investigated by Kreil in his work of that 



