60 New form of Roller for the Disk-and-Roller Integrator. 



prevents the roller from being easily moved with its axis 

 parallel to a radius of the driving-disk. 



The author of this communication has devised and used (in 

 connexion with an ergometer, described in the Philosophical 

 Magazine, vol. xv. p. 87) the following arrangement, whereby 

 the difficulties now mentioned are removed. Instead of the 

 roller being solid, the edge or face of itis notched in a dividing- 

 engine with a circular saw ; each notch so formed carries a 

 little disk, the edge of which is rounded to the curvature of 

 the circle OB, fig. 2 ; a ring of steel piano-wire forms the 

 axis of all the little disks placed round the circumference of 

 the roller R (only two of the little disks, d and d', are shown 

 in fig. 2). In fig. 1 D is part of the large driving-disk 

 which drives the roller R, YY' is the axis of the disk D, XX' 



Fijr. 1. 



Kff. 2. 



x 



that of the roller R. A roller so constructed is found to 

 move with the utmost freedom in the two directions required, 

 and it will do so, without any " slip/' whether the motions are 

 simultaneous or not so. By making the number of little disks 

 round the roller large, and facing the disk D very carefully, 

 Hie action even at a high speed is quite smooth and free 

 from vibration. 



For the theory of the disk-and-roller integrator the reader 

 may consult c Mechanics of Engineering/ J. Weisbach, vol. ii. 

 p. 40, or i 1 ic> l Elements of Mechanism,' Goodove, p. 310. 



Taunton, December 10 t 1883, 



