JAMES WATT. 41 



approach nearer to each other in the opposite circumstances. 

 This alone would have served to indicate the state of matters to 

 the eye ; but Watt was not to be so satisfied. He connected 

 the rods with a valve in the tube by which the steam is admitted 

 to the cylinder from the boiler, in such a way, that as they 

 retreat from each other, they gradually narrow the opening 

 which is so guarded, or enlarge it as they tend to collapse; 

 thus diminishing the supply of steam when the engine is going 

 too fast, and, when it is not going fast enough, enabling it to 

 regain its proper speed by allowing it an increase of aUment. 

 Again, the constant supply of a sufficiency of water to the boiler 

 is secured by an equally simple provision — namely, by z. float 

 resting on the surface of the water, which, as soon as it is car- 

 ried down by the consumption of the water to a certain point, 

 opens a valve and admits more. And so on, through all the 

 different parts of the apparatus, the various wonders of which 

 cannot be better summed up than in the forcible and graphic 

 language of a recent writer : — " In the present perfect state of 

 the engine it appears a thing almost endowed with intelligence. 

 It regulates with perfect accuracy and uniformity the number of 

 its strokes in a given time, counting or recording them, moreover, 

 to tell how much work it has done, as a clock records the beats 

 of its pendulum; — it regulates the quantity of steam admitted to 

 work ; — the briskness of the fire; — the supply of water to the 

 boiler; — the supply of coals to the lire ; — it opens and shuts its 

 t'^/z;^j with absolute precision as to time and manner; — xt oils 

 its joints ; — it takes out any air which may accidentally enter 

 into parts which should be vacuous ; and when anything goes 

 wrong which it cannot of itself rectify, it warns its attendants by 

 ringing a bell ; yet with all these talents and qualities, and even 

 when exerting the power of six hundred horses, it is obedient 



