Experimental P?iilosophi/. [Lecture 16. 



bale up the step of a warehouse, place a board 

 along from the step to the ground, which ren- 

 ders the ascent gradual and easy. The power of 

 the inclined plane is as great as its length exceeds 

 its perpendicular height. For instance, let AB 

 (PI. XXII. fig. 100) be a plane parallel to the 

 horizon, and CD a plane inclined to it ; and sup- 

 pose the whole length CD to be three times as 

 great as the perpendicular height AC ; in this 

 case the cylinder E will be supported upon the 

 plane CD, and kept from rolling down upon it 

 by a power equal to a third part of the weight of 

 the cylinder. Therefore, a weight may be rolled 

 up this inclined plane with a third part of the 

 power which would be sufficient to draw it up 

 by the side of an upright wall. If the plane 

 were four times as long as high, a fourth part of 

 the power would be sufficient ; and so on, in pro- 

 portion. Or, if a weight were to be raised from 

 a floor to the height AC, by means of the ma- 

 chine ABCD, (which would then act as a half 

 wedge, where the resistance gives way only on 

 one side) the machine and weight would be in 

 equilibrio when the power applied at AC was to 

 the weight to be raised as AC to AB ; and if 

 the power is increased, so as to overcome the 

 friction of the machine against the floor and 

 weight, the machine will be driven, and the 

 weight raised ; and when the machine has moved 

 its whole length upon the floor, the weight will 

 be raised to the whole height from A to C. 



