MECHANICAL PARADOXES. 



able difference in their centrifugal weights 

 when they are spinning round, and the heavier 

 one rapidly forces its way to the outer end 

 that is, the bottom of the test-tube. 



In machines made on this principle, though 

 different in detail, large quantities of milk 

 are separated every day, the watery part of 

 the milk being driven to the outer part of the 

 circuit, while the lighter cream remains nearer 

 the centre. The same system is used in large 

 laundries, for rapidly extracting the water 

 from wet clothes, and in apiaries to throw out 

 honey from the cells of the honeycomb without 

 destroying the latter, as formerly, by chopping 

 and crushing them. 



4. Repulsion and Attraction by the Same Agent. 



If a steam-pipe, connected with a boiler 

 in which steam is being raised, be pierced with 

 a small hole, the steam will rush out in a fine 

 jet. The speed at which the steam enters the 

 inner end of the hole is something like 1,400 

 feet per second ; but as it passes along the 

 fine channel it expands, and occupies, after 

 expansion, a greater volume. But when two 

 gallons of anything have to go through an 

 orifice in the same time as one gallon, it is 

 clear that each part of the two gallons must 

 travel twice as fast as each part of the one 

 gallon ; and since each gallon of steam passing 

 the inner end of the hole becomes by its 



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