THE FEINTING PKESS. 



Fig. 4. 



piece, in the upper part of which, is a nut, in which a screw 

 moves the point of which acts upon the upper end of a slider, 

 which is fixed into a dovetailed groove formed between two 

 vertical bars of the frame. This slider has attached to its lower 

 end a square plate, called the platten, which rises and falls 

 according as the screw is^ turned in the one direction or the other. 

 The weight of the platten fig. 3, A, and slider, which is considerable, 

 is counterpoised by a heavy weight c suspended by a lever behind 

 the press. The flat table, called the carriage, upon which the form 

 of types is laid, is moved backwards and forwards by means of, a 

 winch, which appears in fig. 3. By means of this winch, and 

 the rack or band with which it is connected, the carriage with 

 the type form can be moved by the pressman alternately back- 

 wards and forwards, so that it can be brought under the platten, 

 and after having received the pressure, can be removed back to 

 its first position. The platten is made to impart the pressure by 

 means of a lever called the knee lever, an expedient which- is 

 much used in the arts in cases where any intense pressure is 

 required to be produced through a very limited space. The 

 mechanical effect of this species of lever will be understood by a 

 reference to fig. 4, where A B is a metal rod, having a fixed point 



of support A on which it works ; 

 another bar G c is jointed to it 

 at c, a point intermediate be- 

 tween A and B. This bar c G 

 is jointed at G to a plate such 

 as R, or any other object to 

 which it is desired to trans- 

 mit any intense force acting 

 through a very limited space, 

 as, for example, in the present 

 case, where the paper is pressed 

 upon the type by a plate which 

 is driven upon it by a sudden 

 and severe force. The handle 

 B of the lever being pressed in 

 the direction of the arrow, ex- 

 erts a corresponding pressure 

 on the point c, which is driven 

 in the direction c D perpendicular to A B. This motion c D is re- 

 solved into two by the parallelogram of forces, one in the direction 

 c E, and the other in the direction c F ; the latter exerts pressure 

 on the fixed point A, and the other acts upon the plate R by means 

 of the joint G forcing it downwards. As the joint c advances, the 

 angle A c G becomes more and more obtuse, and the component c E 

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