72 



3IECIIAXICS. 



power given to the block, and this relative diiFerence in- 

 creases as the joint is made straighter. 



This power is made use of in the lever printing-press, 

 where the greatest force is given just as the pressure is 

 completed. Another example occurs in the Lever Wash- 

 ing-machine (fig. 79), which is worked hy the alternating 

 motion of the handle, A, pressing a swinging board, per- 



Levcr Washing-inachinc. 



forated with holes, with great force against the clothes 

 next to one side of the water-box. Like the printing- 

 press, this machine exerts the greatest power just as the 

 motion of the lever is completed, and at the time it is 

 most needed. The same principle is exhibited in KendaWs 

 Cheese-press (fig. 80), where the lever and the wheel and 

 axle are combined with the two knee-joints, one on each 

 side of the press, drawing down a cross-beam upon the 

 cheese with a greatly multiplied power. 



Dlclc's Cheese-press (fig. 83), operates on a similar 

 piinciple. Figs. 81-2 shov/ the structure of its working 



