126 Mayow 



a, a^ is the huge mass of sea-water rising up like a 

 pillar or a mountain. This mass is sometimes of 

 greiater, sometimes of less height, and assumes some- 

 times a pyramidal and occasionally an orbicular form. 



c^ c, is a somewhat dense fog produced by the 

 ascent of fine water particles. This, which derives 

 its origin from the aforementioned mass of water^ 

 expands in all directions, but it soon begins to con- 

 tract gradually, and at last ends in a point at e, e. 



e^ e^ /,/, is a gloomy tube which, descending from 

 an overhanging cloud, directly overtops the afore- 

 said column of water. This tube is at first like a 

 stream of smoke, which seems to descend gradually,, 

 yet so as to leave a gap between its lower end and the 

 underlying water. Further, this tube is after a short 

 time filled with a whirling mass of vapours densely 

 crowded together, or it may be of water, which 

 rushes upwards with a most furious motion, with 

 spiral revolution, and a remarkable roaring noise, as 

 is shown in the aforesaid figure. After about ten 

 minutes, a part of the tube, a third say, or a half, is 

 often broken off, and when this happens, the waters 

 rush down in immense quantity — a fearful sight to- 

 behold — and ships are sometimes sunk by them. 



d^ d^ is the cloud from which the said tube is seen 

 to descend. It is at its first appearance small and 

 thin, but it soon expands widely in all directions, and 

 at last, when it has become exceedingly dense and 

 gloomy, it dissolves in a violent storm of rain. Sq 

 much then by way of description of the phenomenon^ 

 It now remains for me to show next the way in which 

 it is produced by a whirling movement of the air 

 and by its diminished pressure. 



And here in the first place I take it for granted 

 that the air is sometimes driven round in a circle^ 



