THEORY CONFIRMED BY PHENOMENA. 43 



in the middle of a room, without .deranging some piles of 

 china ware in it. 



71. No one can doubt that the hail which fell almost im- 

 mediately after the passage of the spout, was connected 

 in some way with the spout itself. The manner of its con- 

 nexion is fully explained by the theory. And even the per- 

 fect calm which reigned a short distance beyond the borders 

 of the spout, which, in this instance, was very narrow, may 

 easily be imagined from the outspreading of the air above, 

 causing an increased pressure on the barometer, and thus 

 preventing the air, beyond a certain distance, from moving 

 towards the spout at the surface of the earth, and beyond this 

 point even causing it to move in an opposite direction. 



72. The direction, also, in which the latter spout leaned, 

 may also be accounted for on supposition that the upper 

 part of it reached the current of air which, in higher regions 

 of the atmosphere, is always moving from the south west 

 to the north east ; for, as soon as it reached that current, its 

 upper part would be blown in that direction, and the spout 

 itself would have to move in that direction with it. More- 

 over, the spout would be stationary, if it was formed in still 

 air, until its upper part should reach this upper current, 

 which might be twenty or thirty seconds, and this will ac- 

 count for the excavation of the earth under the place where 

 the spout was seen to be formed. 



73. Again, the theory will account for the rebounding of 

 the spout that is, of its sometimes reaching the surface of 

 the earth, and sometimes not. For, where the dew point 

 was very near the temperature of the air, there a very slight 

 rarefaction of air would produce cold enough to cause a con- 

 densation of the vapor, and so the vortex, with its condensed 

 vapor, would be seen to reach the earth, and vice versa, 

 where the dew point should be many degrees below the 

 temperature of the air. 



On the principles established in the first section, (22), the 



