440 M. Abich on Hailstorms in Russian Georgia. 



cause the thunderstorm rising in the Ararat region either to 

 exhaust itself in the Lesser Ararat, or to pass it rapidly and to 

 spread over the whole opposite plain. The facts and observa- 

 tions above mentioned seem to confirm MM. Peltier and La- 

 mont's views on the origin of thunderstorms and of atmospheric 

 electricity. 



LII. Hailstorms in Russian Georgia. By M. Abich*. 

 [With a Plate.] 



THE first of these storms took place May 27, 1869, at 

 3 p.m., the other June 6, at 6 p.m., both within a limited 

 region of the Trialat Mountains near Beloi Kliutsch, about forty 

 wersts (26| Engl, miles) from Tiflis. The hailstones, although 

 different in form in both cases, were of uncommon size, and 

 deserve some attention. In the first case they presented a 

 quite regular flattened spheroidal form, somewhat like the so- 

 called "mandarin-oranges," and a series of varieties almost re- 

 minding one of organic evolution. The second case was a com- 

 plete " shower of ice crystals" — not of fragments of ice of indi- 

 stinctly crystalline outlines, but of spheroidal crystalloid solids, 

 densely but irregularly beset, on the surfaces corresponding to 

 their longitudinal diameter, with limpid regular crystals showing 

 various combinations of forms belonging to the tri- and mono- 

 axial systems — a peculiarity which, it seems, has not yet been 

 observed, or at least published. The forms characteristic of 

 calcareous spar and of specular oxide of iron prevailed, especially 

 the scalenohedron, combined with rhombic planes, in crystals 

 15 to 20 millims. in length. Other crystals exhibit the prism, 

 combined with obtuse rhombohedra, and with the terminal plane 

 perpendicular to the principal axis. Some specimens that fell 

 soon after the beginning of the storm were aggregations of 

 tabular crystals, 30 to 40 millims. in diameter, resembling the 

 rosette-like aggregations of specular oxide of iron from Mount 

 S G otthardt. 



Both these storms caused enormous devastations; strong 

 branches were struck down as if cut with some sharp implement. 

 The specimens gathered immediately after the fall presented 

 perfectly sharp edges and somewhat convex surfaces, like some 

 crystals of diamond — except the scalenohedral surfaces, which 

 were completely flat. M. Abich made drawings from ten of the 

 most remarkable and best preserved specimens, intending to pub- 

 lish in extenso his observations on the phenomena in question. 

 These hailstorms have a close connexion with the abnormal me- 



* From a letter to Chevalier W. de Ilaidinger, dated Tiflis, June 25, 

 18G9. Communicated and translated by Count Marschall, F.C.G.S. &c. 



