168 Intelligence and Miscellaneous Articles. 



enough to form eddies, or the liquid behind the obstacle comes to 

 rest, and these are stationary and almost immoveable points. 



These are good conditions for the formation of ice at the bottom 

 of rivers. The eddying motion produced by obstacles brings cold 

 water to the bottom and cools the sides ; and the molecules of water 

 behind the obstacle exert their adhesive force and crystallize. But 

 to produce these effects an intense and continuous cold is necessary. 



In conclusion, the author attributes the formation of ground ice to 

 obstacles in the current, which on the one hand, by the eddying 

 motion, cause the water below 0° to sink to the bottom and cool the 

 sides, and on the other hand produce stationary parts in which the 

 crystallizing power can exert its force. He observed the influence of 

 these foreign bodies in a conduit at Zinsweiler. In 1829, ice formed 

 at the bottom of the water in which there were large stones, trees, 

 &c. The formation of ice was entirely prevented by removing these 

 foreign bodies.— Comp tes Rendus, July 2, 1860. 



ON A REMARKABLE ICE SHOWER. BY CAPTAIN BLAKISTON, R.A. 

 [Extract of a Letter to General Sabine, R.A.] 



"On the 14th January, 1860, when two days out from the Cape 

 of Good Hope, about three hundred miles S.S.E. of it, in lat. 38° 

 53' S., long. 20° 45' E., we encountered a heavy squall with rain 

 at 10 a.m., lasting one hour, the wind shifting suddenly from east 

 to north (true). During the squall there were three vivid flashes of 

 lightning, one of which was very close to the ship ; and at the same 

 time a shower of ice fell, which lasted about three minutes. It was 

 not hail, but irregular-shaped pieces of solid ice, of different dimen- 

 sions, up to the size of half a brick. The squall was so heavy that 

 the topsails were let go. 



" There appears to have been no previous indication of this squall ; 

 for the barometer at 6 p.m. on the two previous days had been at 

 30-00, therm. 70°; at 8 a.m. on the 14th, 29*82, therm. 70°; at 

 10 a.m. (time of squall), 29*86, therm. 70° ; and at 1 p.m., when the 

 weather had cleared, wind north (true), 29*76, therm. 69° ; after 

 which it fell slowly and steadily during the remainder of the day and 

 following night*. 



" As to the size of the pieces of ice which fell, two, which were 

 weighed after having melted considerably, were 3£ and 5 ounces 

 respectively ; while I had one piece given me, a good quarter of an 

 hour after the squall, which would only just go into an ordinary 

 tumbler. And one or two persons depose to having seen pieces the 

 size of a brick. 



" On examination of the ship's sails afterwards, they were found to 

 be perforated in numerous places with small holes. A very thick 

 glass cover to one of the compasses was broken. 

 • " Although several persons were struck, and some knocked down 

 on the deck, fortunately no one was seriously injured." — From the 

 Proceedings of the Royal Society for May 3, 1860. 



* The weather on the morning preceding the squall was clouded, with close and 

 thick atmosphere, wind E. (true), 3. By night of the 14th the wind had hauled 

 to N.W. (true), 4; and the day following was W.S.W. (true), 5—6, cloudy. 



