I50 THE DISPERSAL OF SHELLS. 



up the dust which lay in the road, in the form of a 

 sugar-loaf with the pointed end downwards, and soon 

 after grew to the height of forty or fifty feet, being 

 twenty or thirty in diameter. It advanced in a direc- 

 tion contrary to the wind ; and although the rotatory 

 motion of the column was surprisingly rapid, its onward 

 progress was sufficiently slow to allow a man to keep 

 pace with it on foot. Franklin followed it on horse- 

 back, accompanied by his son, for three quarters of a 

 mile, and saw it enter a wood, where it twisted and 

 turned round large trees with surprising force. These 

 were carried up in a spiral line, and were seen flying in 

 the air^ together with boughs and innumerable leaves, 

 which, from their height, appeared reduced to the size 

 of flies." ' 



The following account of a whirlwind in Ireland in 

 1872, was printed in Nature in that year: 



'' In a letter to the Belfast Neivs-Lettcr, Mr. C. J. Webb 

 describes an extraordinary whirlwind which occurred in 

 the district around Randalstown, about six miles north- 

 west of Antrim, near the shores of Lough Neagh, on 

 the 25th of August last [1872]. The same phenomenon 

 was witnessed about an hour and a half earlier the 

 same evening at Banbridge, about seven miles south- 

 west of Dromore. It was first seen near Randalstown 

 about 5 p.m. between that place and Toome, moving 

 rapidly up Lough Neagh from the south, and presenting 

 the appearance of a defined column of spray and clouds, 



^ " Principles,'' ii. p. 392. 



