156 



BENJ. PIKES, JR., DESCRIPTIVE CATALOGUE. 



at a distance of six inches on the upright arm ; the cord in 

 this case also passing over and being supported by one of 

 the movable pulleys, B. Each of the levers on the upper 

 frame may be moved, or taken away, by loosening the thumb 

 screw attached, and the two levers may be arranged to illus- 

 trate a compound lever, and also may be arranged for this 

 purpose, connected with the lever A, attached to the pillar. 



The Inclined Plane, represented in Fig. 171, consists of a 

 mahogany board, about 16 inches long and 3 or 4 inches 

 wide, hinged on the top of the frame and movable, having a 

 graduated arch, with screw to fasten it at any angle required. 



Fig. 161. 



There is a pulley at the end for supporting a cord from the 

 carriage, which carriage is on three wheels, and weighs ex- 

 actly four ounces. If the inclined plane be fixed at a height 

 equal to one-half the length of the plane and the carriage 

 placed thereon, having a cord passed over the pulley, and a 

 weight of two ounces attached thereto, it will be exactly 

 balanced ; or if the inclined plane be fixed at a height equal 

 to one-fourth the length of the plane, one ounce attached to 



