WATT. 41 



this lessens the supply of steam ; the motion of the 

 engine is thus reduced, the centrifugal force is abated, 

 the balls approach the spindle again, the collar de- 

 scends, the throttle-valve is gradually opened, and the 

 supply of steam again slowly increased, but never be- 

 yond the quantity required, because as soon as that is 

 exceeded, the increase of centrifugal force causes the 

 balls to diverge, the collars to rise, and the valve to 

 close. Thus the engine itself provides for its conti- 

 nuing in the state of perfect adjustment required. As 

 long as its motion continues uniform, the balls revolve 

 at the mean distance from their axis without either 

 receding or approaching, and the supply of steam con- 

 tinues the same. As soon as the motion becomes ex- 

 cessive, they diverge, and the supply of steam is dim- 

 inished ; as soon as the motion becomes defective, they 

 converge, and the supply of steam is increased. But 

 further, the balls themselves, by their increased motion, 

 absorb part of the force, independent of their action on 

 the throttle-valve, and so contribute to the adjustment. 

 The sagacious inventor soon satisfied himself that 

 he had almost created a new engine of incalculable 

 power, universal application, and inestimable value. 

 But he had not the funds either to try his invention 

 upon an adequate scale so as to bring it into use, or to 

 secure his property in it by obtaining a patent. After 

 some repulses, he happily met with Dr. Roebuck, a 

 man of profound scientific knowledge, and of daring 

 spirit as a speculator. He had just founded the Carron 

 Iron Works, not far from Glasgow, and was lessee, 

 under the Hamilton family, of the Kinneil Coal Works. 

 He was the grandfather of the present Member for 

 Bath, who, descended from him on the one side, and 

 from the Tickells* on the other, may be said ^to unite 

 in himself rare claims to hereditary distinction ; but 

 who is probably destined to exalt the name of his 



* His maternal grandfather was the author of 'Anticipation,' and 

 grandson of Addison's friend, the poet. 



