140 TRANSACTIONS OF THE 



The bevel wheel (I) is on an arm of a horizontal hub (S), which 

 turns freely on the hub of tlie vertical stand (R), and this hub 

 carries a horizontal cogged segment (S'), the cogs of which engage 

 the cogs of rack (M), adapted to slide in suitable ways in the base 

 of the column. When the hub (S) of the bevel wheel (I) is held 

 in a fixed position by the rack (M), the rotation of the driving 

 pulley which imparts motion to the bevel wheel (I^) by the wheels 

 (K) and (K'), rotates the shaft (F) in the reverse direction of the 

 wheel (1), because the motion imparted by the wheel (I') to (I) is 

 then all transmitted to the wheel (II) attached to the shaft; but 

 if the shaft (F) be held so that it cannot rotate, and the hub (S) 

 on which the wheel (I) is mounted, be free to turn on the hub of 

 the vertical stand (R), then all the motion imparted to the wheel 

 (I) by the wheel (I'), will cause the said wheel (I) to revolve 

 about the shaft (F). 



For the purpose of holding the axis of the wheel (I), a cliain 

 (0) is attached to the rack (M), passes over a guide pulley (N), 

 and has a weight or spring (P) attached to it, which weight or 

 spring tends constantly to force the rack in one direction, and to 

 resist the tendency of the hub (S) to be turned by the driving 

 power which rotates the wheel (I), and therefore so long as the 

 power required to turn the shaft (F) is less than the power 

 required to lift the weight or spring (P), the shaft (F) will be 

 rotated by the driving pulley (L) through the intermediate gear- 

 ing, but as soon as the resistance on the shaft (F) is increased 

 beyond the power required to lift the weight or spriug (P), the 

 wheel (I) will begin to travel or revolve about the axis of the shaft 

 (F), which will cause the rack (M) to be moved in the direction 

 to lift the weight or spring (P), and to the extent of this motion 

 the shaft (F) will be retarded. On the upper end of the shaft (F) 

 there is a cross-head (W), forming two horizontal arms, to the 

 ends of which are hung, by joint pins (EE), the rods (TT), 

 of the usual governor balls (UU), which are prevented from fall- 

 ing below a certain elevation by spurs (ad), which strike against 

 stop pins (gg), on the arms or cross-head (W). 



The under face of the spurs (aa) are cam-formed, and act on 

 the upper end of a cap (c), which is free to slide up and down on 



