82 



GREENWOOD MACHINE. 



from the knife edges on the end of the first-motion lever 

 vertically upwards to the knife edges on the short end of 

 the second lever. A downward motion of the jockey 

 wi-i^hts raises these links, and with them the long arm of 

 the first lever, and so increases the pull on a specimen held 

 in the jaws. The long weight which hangs from the short 



arm of the second lever is simply a counter poise to balance 



the weight of the long arm. 



The total 



leverage 



of this machine is 100 to 1 ; the 



