180 Mr. Charles Tomlinson on 



the freezing region, or even be stationary. They may be 

 carried from the vortex ont where the velocity of the ascend- 

 ing current is small, and dropping down some distance may 

 then be carried in towards the vortex by the inflowing current 

 on all sides, and up again rapidly into the freezing region. 



The nucleus of large hailstones is generally composed of 

 compact snow. A small ball of snow saturated with unfrozen 

 rain, which is carried up into the snow-cloud, is formed in 

 that region and freezes, and being of less specific gravity 

 than compact hail is kept where it receives a thick coating 

 from the rain carried up, as in the case of the small hail, and 

 afterwards falls to the earth, either at some distance from the 

 centre, where the ascending currents are weak, or near the 

 vortex after the rapidity of the ascending currents has become 

 sufficiently diminished. As there may be in the case of cloud- 

 bursts a great accumulation of rain, and a sudden down- 

 pouring of it, all in a short time, so in a hail-storm a great 

 quantity of hail may be collected in the lower part of the 

 cloud, brought in by inflowing currents on all sides towards 

 the vortex, after the ascending currents have become too weak 

 to carry it up and again throw it out above, and are still too 

 strong to permit it to fall. But soon the interior of the 

 tornado becomes so overloaded, and the energy of the whole 

 system so much spent that the hail falls to the earth almost at 

 once. Hence the large quantities of hail which sometimes fall 

 in a short time. 



-When a hailstone is carried up in or near the vortex, and 

 carried out above to where the ascending current is too feeble 

 to sustain it in the air, it gradually drops down, and the inflow- 

 ing current draws it in towards the vortex, where it is again 

 carried up, and thus describes a sort of oval orbit. It may 

 be thrown up very high into the snow-cloud region, or but 

 little above its base. It may describe a number of such 

 orbits or revolutions before it falls to the earth. While high 

 up in the snow-cloud region it receives a coating of snow; 

 and then, while descending very gently, where the strength 

 of the currents is not quite sufficient to sustain it, and near 

 the base of the snow region, where rain yet unfrozen is carried 

 up, it receives a coating of solid ice, which may be continued 

 for some time after it falls into the rain-cloud, since the hail- 

 stone still continues for some time below zero. After a short 

 time the inflowing current below draws it again into the 

 vortex, where it is again thrown up into the snow-region to 

 receive a new coating of snow. It thus receives alternate 

 coatings of snow and ice, and the number of each sort denotes 

 the number of revolutions described before it falls to the 



