FOR AMERICAN VINES. 



17 



<J, will travel ten times slower than if the force P, was 

 applied directly with the same velocity ; or, what is the 

 same, it will take ten times longer to raise the weight. 



The windlass arranged as shown in Fig. 1 may also 

 serve to raise loads. It forms the essential part of the 

 machine known as the lifting crab, which is used in building 

 to raise stones and timbers. The lever I may be replaced by 

 a winch-handle made fast to one of the axle-trees passing 

 through a socket. In the quarry windlass a large wheel of 

 13 to 19 feet in diameter replaces the levers. It is provided 

 with bars. Men mount these bars as if on a ladder, and it 

 is their weight which constitutes the moving power. 



If the axis of the windlass is vertical instead of horizontal, 

 and if, therefore, the levers rotate in a horizontal plane, the 

 machine takes the name of capstan. The conditions of 

 equilibrium are evidently the same. Under this form the 

 capstan is sometimes used in cellars to work wine-presses ; 

 the rope is fixed on the bar of the press, and men work the 

 winding drum of the capstan with capstan bars. 



To attain still greater traction, toothed wheel gearing 

 may be interposed between the motive power and the 

 resistance. Fig. 2 shows diagrammatically the toothed- 

 wheel gearing. The drum t carries a toothed wheel R' geared 

 with a pinion /. On the shaft of this pinion a toothed 

 wheel R is fixed gearing with a pinion r, on the shaft of 



6279. 



Fig-. 2. - Toothed-wheel gearing. 

 B 



