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 may 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 orbicular 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 system @ 
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 oF 
quite to a point vertically above the centre of the wheel. ' 
11. Replace the frame on its base B, and make the arrangement 
exhibited in Fig. 1. By the combined action of the rotary motion © 
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 / towards 
all points of that circle in succession, so as to generate a cone; 0 
which the apex is at the point where the thread 1 is fastened to the 
upper part of the frame. 
12. The rotascope may be made to answer several of the pul 
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 scr 
s,s. The pullies p, p, being raised nearly to the top of 
pieces of the frame, are placed ona level with each other: Hang 
two equal weights one at each end of a cord, and place it over - 
pullies, care being taken to bring the two to the same Jevel- fk 
pend a weight to the middle point between the two pullies sufficie? 
to depress the cord about 30° or 40° from the horizontal pose”: 
