110 PHYSIOLOGY OF THE CIRCULATION. 



should represent more or less of the appearance of a 

 rapidly diverging cone. 



As before mentioned, it has also been proved by 

 the experiments of Venturi and others, that when a 

 rapid stream traverses a short conical tube, the 

 whole surface of that stream possesses the power of 

 drawing into the tube any stagnant fluid with which 

 (by means of a lateral opening) the interior of that 

 tube may communicate ; and in repeating these 

 experiments with a strong jet, I have found the same 

 ascent and influx of the external stagnant fluid to 



O 



occur, whether the communicating glass tube were 

 fastened to the upper, or lower, or lateral, surface of 

 the main pipe. 



In explanation of this phenomenon, it may be 

 stated, as a general principle, that all bodies, while in 

 a state of rapid motion, possess the power of carrying 

 with them the contiguous particles of any surrounding 

 stagnant fluid. Thus a jet of liquid, or one of gas, 

 or a rapidly revolving wheel, or any projectile, will 

 each speedily cause a current of the surrounding air 

 to flow in the same direction. 



I have even found that, on holding the orifice of a 

 glass tube at a right angle to the surface of a strong 

 jet of water, the ascent and discharge into the stream 

 of the liquid into which the other end of the glass 

 tube dipped took place with the same rapidity as 

 when the jet traversed a rigid pipe.* Hence it 

 appears that a stream can exercise an active ab- 



* A detailed account of tins and some anulo-ous experiments 

 was contained in a Paper lately read lieforc the IJoval Society. 



