Causes of Water Spouts. 49 



being entirely immersed in the liquid. I then caused the mill to re- 

 volve about twice in a second, and after continuing the motion for a 

 minute, the water at the. bottom began to whirl round and to rise a 

 little in a conical form, and soon after, from the summit of the little 

 cone a fine column of water sprung up all of a sudden, until it got 

 into the vanes of the mill. (Fig. 1.) 



This little water spout rising through the oil, was about two lines 

 in diameter and resembled a tube of flexible glass ; the water which 

 it brought up into the mill was driven to the circumference of the 

 whirl and descended afterwards in small drops with a narrow screw 

 motion to the bottom, but so slowly that it was quite practicable to 

 cause all the water to rise and mingle with the oil. 



As the latter liquid easily loses its transparency by its mixture with 

 the water and as it was nevertheless necessary to examine the motion 

 of the whirl in all its parts, I instituted the following experiment. 



Second Experiment. — I filled with pure water another vessel two 

 feet high and nine inches in diameter, and threw into it an ounce of 

 copaly coarsely pulverised ; this substance having a specific gravity 

 very little superior to that of water, remains a long time suspended, 

 and yields to the slightest motion of the fluid which it renders visible. 

 I adjusted the mill as in the last experiment. 



When I commenced the experiment the coarser pieces of copal 

 formed a layer at the bottom and the finer remained suspended. At 

 the first turn of the mill, those in the direction of the axis ascended 

 rapidly into the vanes, and those near the circumference took a spi- 

 ral movement which carried them toward the bottom of the vessel. 

 This whirling was propagated from layer to layer by means of these 

 two motions, and when it had reached the particles at the bottom 

 they rose, like the water in the first experiment but in a much thick- 

 er column, being from four to six lines in diameter, and ascended 

 into the vanes of the mill, thus rendering the whirling spout very dis- 

 tinctly obvious. 



To be able to follow a single isolated particle throughout its 

 march, I threw in a few fragments of gum lac, which were easily 

 distinguished by their red color. They were seen ascending rapid- 

 ly in the center in the direction of a very elongated helix ; the mill 

 threw them to various distances according to their sizes and drove 

 them in narrow spirals to the bottom, where they were brought again 

 to the center to renew the same sport. 



Vol. XXV.— No. 1. 7 



