48 



THE APPLICATIONS OF PHYSICAL FORCES. [BOOK i. 



the taper end is sufficient to hold it in the tube ; but if the finger is 

 raised and air is admitted, the exterior pressure on the inner surface 

 at once counterbalances that on the lower level of 

 the liquid, and the liquid flows out by its weight. 

 It is also possible to stop the efflux of the 

 liquid or recommence it at pleasure by the simple 

 movement of the finger. This is done by those 

 who show amusing physical experiments witli 

 the magic funnel or the inexhaustible bottle. We 

 can easily account -for the working of these. 



Fig. 28 represents the magic funnel. It is a 

 double funnel, the inner and invisible cavity is 

 filled with a liquid, wine, for instance. A small 

 opening, worked near the handle, is closed or 

 opened with the thumb, and a small inner, hole 

 connects the cavity full of liquid with the visible 

 inner tube of the funnel. When the thumb is 

 lifted, the wine runs out. The flow of the liquid 

 ceases at the will of the operator, if he closes the 

 upper opening. 



If water is poured into the visible space of the funnel, pure 

 water will flow out, or a mixture of water and wine, according as the 



FIG. 27. Pipette. 



FIG. 28. - The magic funnel. 



opening of the handle shall be closed or open. The spectators then 

 believe that water or wine may be made to flow from the magic 

 funnel at pleasure. 



