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THE MECHANICAL POWERS. 



THE SCREW. 



The screw is a revolving inclined plane, or an inclined 

 plane wound round a cylinder. Hence, when its length and 

 its pitch, or height, are ascertained, the same rules that 

 govern the inclined plane apply to the screw. 



To find the length of the inclined plane of a screw. 



RULE. Add the square of the circumference of the screw 

 to the square of the pitch, or distance between the threads, 

 and take the square root of the same, which will be the 

 length of the plane. The height is the distance between 

 the consecutive threads. 



