QO CURRENTS PRODUCE A VACUUM. 



tical atmospheric vibrations, while their action on 

 the surface of the surrounding water continues 

 undiminished, the external vibrations predominate, 

 forcing the water to ascend in the perpendicular 

 pipe B, and to flow in a continuous stream from 

 the end of the pipe c. 



A similar arrangement, called " Gifford's 

 Injector," is now commonly used for feeding 

 steam-boilers as a convenient substitute for a 

 forcing pump. 1 



A beautiful illustration of the impinging of 

 vibrations against the sides of bodies is seen in 

 placing a light ball or globe in contact with the 

 ascending current of a jet oTeau. The ball rises 

 with the current and clings to it ; being propelled 

 up as often as it tends to fall. The ascending 

 stream converts the atmospheric vibrations against 

 the side of the ball next the stream into paral- 

 lel currents ; whereby the continuous vibrations 

 against the outer side of the ball predominate, 

 and produce a resultant movement of the ball 

 toward the centre of the stream. 



As with terrestrial so with celestial magnetic 

 currents ; the stronger will always overpower the 



1 A simple plan of producing an atmospheric vacuum, as a substitute 

 for an air-pump, is also used on railroads for operating brakes to check 

 the speed of locomotives. The blast of a jet of steam over the end of a 

 pipe connected with a cylinder having two movable pistons, arranged as 

 air-tight heads, forms a vacuum in the cylinder, that allows the external 

 vibrations to press simultaneously against both of the movable pistons, 

 producing their resultant movement toward the middle of the exhausted 

 cylinder. Rods attached to each of the two piston-heads then draw in the 

 friction brakes against the rims of the wheels, and check their speed. 



