500 Description of a Steam- Evgine 



However plausible the above may appear in theory, no 

 doubt difficulties will occur when we attempt to reduce it 

 into practice. But I am persuaded they will not be found 

 insuperable. 



The only experiment I have hitherto made on this subject 

 has been merely to show that a pendulum can be made in 

 this manner which shall vibrate quicker in a dense medium 

 than in one more rare, contrary to what takes place with 

 common pendulums, 



I made a compound pendulum, on the principles above 

 mentioned, of about one foot in its whole length. This pen- 

 dulum, on many trials, made in the air 57 vibrations in a 

 minute. On immersing the whole in water it made 59 vibra- 

 tions in the same time, showing evidently that its motion was 

 quicker in so dense a medium as water than in the air. "When 

 the lower bob or pendulum only was plunged in water, it 

 made no more than 44 vibrations in a minute ; the remain- 

 ing 15 being solely the effect of the pressure of the water 

 against the upper vessel C. 



XXXVIII. Description of a new invented Steam- Engijte, 

 intended to give Motion to JVater Wheels in Places where 

 there is no Fall, and but a very small Stream or Spring, 

 By John Nancarhow*. 



A, (Plate VI 1. fig. 2.) the receiver, vy'hich may be made 

 either of wood or iron. 



B, B, B, B, B, wooden or cast-iron pipes, for conveying the 

 water to the receiver, and. thence to the penstock. 



C, the penstock or cistern. 



D, the water-wheel. 



E, the boiler, which may be either iron or copper. 



F, the hot-well for supplying the boiler with water. 



G,G, two cisterns under the level of the water, in which 

 the small bores B, B, and the condenser are contained. 



* Tiom the Tramactions of the American Philosophical Society. 



HUH, 



