250 Phenomena and Causes of Hail Storms. 



from the latitude of 30° or from the confines of the torrid zone, 

 and the other from the latitude of 50° or the northern part of 

 British America. If they had equal velocities, they would meet 

 at the parallel of 40°, that is, at our own latitude, in ten hours 

 from the time of setting out ; and according to what has been 

 premised, each current would retain nearly the original tempera- 

 ture. The southerly wind blowing from a point which is still 

 two thousand feet below the line of perpetual congelation, is 

 comparatively warm ; while the northerly wind coming from a 

 point which is four thousand feet above the same boundary of 

 the empire of frost, will have a degree of cold pVobably surpass- 

 ing any with which we are acquainted. We infer from our 

 preliminary principles, that immediately on meeting, the watery 

 vapovu' of the warmer current would be frozen with an intensity 

 corresponding to the temperature of the colder current ; that the 

 minute hailstones thus formed, and endued with such exces- 

 sive cold, would begin to descend, and accumulate to a size pro- 

 portioned to the intensity of the cold of the original nucleus — to 

 the space through which they descended — and to the humidity of 

 the lower strata of the atmosphere ; that is, the colder they were 

 when they began to fall, the farther they fell, and the more hu- 

 mid the air, the larger they would become. 



We have supposed a strong case, namely, that a wind from 

 the torrid zone is suddenly brought into contact with a wind 

 coming directly from a point far within the limits of perpetual 

 frost, a concurrence of circumstances which appears to be not 

 improbable, and which appears also sufficient to explain 

 the most extraordinary phenomena of hail-storms. But since 

 natural causes do not commonly operate in their greatest 

 possible energy, it is probable that hail-storms usually result 

 from these causes acting under circumstances less favourable 

 in various degrees. We need not even suppose any thing 

 more than that the cold current, instead of meeting with an op- 

 posite hot wind, merely mixes with the stationary air of the hot- 

 ter climates, in order to precipitate their moisture in the form of 

 hail. In every minute description of a violent hail-storm, how- 

 ever, we shall probably find mention made of this common cir- 

 cumstance, that opposite and violent winds met *, hurrying on 



" Clark in Am. Jour, ii, 134. Beccaria on Elec. in Priestley, 341. 



