530 Note on the Hail-storm of Thursday the Mth March, [No. 5 



Note on the hailstorm of Thursday the 24-th March. — By Henry F. 

 BlanforDj A. B. S. M.j F. G. S. 7 Joint Secretary of the Asiatic 

 Society. 



[Eeeeived 6th April, 1864.— Bead 6th April, 1864.] 



< The formation of hall is well .known to be one of the most obscure 

 phenomena of meteorology, more especially in the case of hail-sloneg 

 of unusual size , which, from the very circumstances of the case, must be 

 formed within the space of the few seconds succeeding the consolidation 

 of "their nuclei, and during which they -are falling, in obedience to the 

 law of gravity. In tropical climates, where the temperature at a 

 considerable height from the earth is much above the freezing point, 

 and where nevertheless, gome of the largest recorded hail-stones have 

 fallen, the stones must attain their maximum dimensions in the first 

 portion of their fall, and during some subsequent seconds, must be subject 

 to the liquifying influence of the lower and denser strata of the atmos- 

 phere. It has appeared to me therefore, that a few observations, on the 

 stones which fell in Calcutta in a hail-storm on Thursday the 24tli 

 ultimo, may be not without interest as a contribution to this branch of 

 Meteorology. For the thermometric, barometric and anemometric ob- 

 servations I am indebted to Col. Thuillier, the Surveyor- General, 

 '■ The storm commenced about J to 6 in the afternoon, the wind being 

 from the south-east, and for a few minutes previous to the fall blowing 

 in strong intermittent gusts, though not stronger than commonly pre- 

 cede the afternoon showers of this season.* The clouds, a thick mass 

 of nimbus, approached or formed from the north-west, but did not 

 move at any great rate, and indeed they appeared to be stationary 

 during the latter part of the storm. Lightning was frequent, and forked, 

 radiating in zig-zags from a small mass of cloud to those around, and 

 the thunder was frequent and almost continuous, but not loud. Heavy 

 drops of rain began to fall at ^ to 6, and were- soon accompanied by B, few 

 hail- stones about the size of hazel nuts. They were not very numerous 



# At the Botanic Gardens, the stillness of which is more favourable to observ- 

 ation than the noise of Chowringhee, Dr. Anderson noticed that the storm was 

 preceded by a prolonged rushing sound, similar to that which would be pro- 

 duced by a number of railway trains rushing by at no great distance. This 

 increased gradually, apparently from the north or north by west, and appeared 

 to pass overhead, before the hail fell. The direction of the hail near the ground 

 was from the south-east. 



