276 Description of the Rotascope. 



to the other side of the arc, where it will be again arrested by the 

 resistance of the wheel, and thus it rnay be made to perform several 

 oscillations before the wheel comes to rest. 



8. Set or suspend the frame on the orbit-rod, give the wheel a 

 moderate velocity of rotation, and set the whole in motion upon the 

 pivot e, all the circles being free to move on their respective axes. 

 In whatever direction the wheel revolves, with respect to the plane 

 of the orbit, at the commencement of the or&fcwZar revolution, it will 

 soon be observed to conform in direction with the latter. If this be 

 reversed, that also will soon be reversed. 



9. Repeat the eighth experiment with only the addition of a weight 

 of some ounces attached to the second circle, opposite to the axis of 

 the first. The effort of the wheel to take, and maintain in its rota- 

 tion, the direction of the orbicular motion, will be sufficient to keep 

 the weight elevated nearly to a level with the centre of the wheel. 



10. Bring circle 3 to a vertical position, and fix it by the grooved 

 wedge. Fix circle 2 in a position at right angles to 3, (its axis of 

 course being vertical,) by cords extending to the side pieces of the 

 frame; suspend a weight on ring 1, and give the whole systefh a 

 motion in the orbit. In order to allow the wheel to take its position 

 nearly coincident with the plane of the orbit, and a direction corres- 

 ponding with that of the system, the weight will be raised nearly or 

 quite to a point vertically above the centre of the wheel. 



11. Replace the/ra?ne on its base B, and make the arrangement 

 exhibited in Fig. 1. By the combined action of the rotary motion of 

 the wheel, and the gravity of the weights W, W, the poles of circle 

 1 will be carried round in a circle, and will stretch the line I towards 

 all points of that circle in succession, so as to generate a cone, of 

 which the apex is at the point where the thread I is fastened to the 

 upper part of the frame. 



12. The rotascope may be made to answer several of the pur- 

 poses of the whirling table. For this object, and especially for ex- 

 hibiting and measuring centrifugal force, the brass circles and the 

 wheel, may be removed from the frame F, by loosening the screws 

 s, s. The pullies p, p, being raised nearly to the top of the side 

 pieces of the frame, are placed on a level vi^ith each other. Hang 

 two equal weights one at each end of a cord, and place it over these 

 pullies, care being taken to bring the two to the same level. Sus- 

 pend a weight to the middle point between the two pullies sufficient 

 to depress the cord about 30° or 40^^ from the horizontal position. 



