

WILLIAM SIEMENS, F.R.S. 123 



If the liquid employed is water, the 1'6 Hire represents 1'6 



kilogram., and the resistance produced by 1 per cent, increase of 



ity is 1'G x '745 = l"2 kilogrammetres per second, which is 



equivalent to forcing a valve rod or lever through one decimetre 



space in fen seconds against a resistance of 120 kilograms. 



This force exceeds by far what is usually required of a governor, 

 and fits the new instrument for the accomplishment of objects 

 which could hitherto not be attempted, such for instance as regu- 

 lating the power of engines by the link motion or other variable 

 expansion gear (whereby a considerable saving of fuel may be 

 effected), or moving the gate of a water-wheel. 



The most striking feature of this governor is, however, the 

 rapidity with which a readjustment between power and load of an 

 engine is effected ; experiment has proved that two-thirds of the 

 Mai load upon an engine may be suddenly thrown off without pro- 

 ducing any visible change in its rotation. It must be borne in mind 

 that the variation of 1 per cent., which was assumed in calculating 

 the power of the instrument, applies only to the short period of ten 

 seconds, when the readjustment of the valve is effected, after which 

 the cup and, with it, the engine returns to its normal rate of rota- 

 tion ; but an increase or decrease of speed of 1 per cent, during ten 

 seconds is so small a total amount that it is not perceptible to the 

 eye, and may be regarded as non-existing for practical purposes. 



A uniform velocity of engines, such as is secured by this 

 instrument, is of considerable practical importance in spinning, 

 grinding corn, and other manufacturing operations, because it not 

 only prevents breakages and irregularities in the quality of the 

 work produced, but it enables manufacturers to attain to the 

 maximum speed at which their work can be produced. 



It has been shown that the rotating cup is not sensitive to 

 tipping, a circumstance rendering the gyrometric governor also 

 applicable to marine engines, which are much in need of a means 

 for maintaining a uniform speed, particularly where the screw 

 propeller is used, which, in being raised by waves above the water, 

 allows the engine to fly off at a dangerous speed. 



The gyrometric cup appears therefore to be equally applicable 

 for maintaining powerful machinery at a nearly uniform velocity 

 and for obtaining the higher uniformity of rotation requisite for 

 philosophical and telegraphic instruments. 



