Description of a new Boiler, etc. 353 



it is only required to heat liquids in an open boiler, 

 this, and another motive, which it would be useless to 

 mention in this place, have lately induced me to con- 

 struct one here (at Paris) and to present it to the In- 

 stitute. 



The object chiefly had in view in the construction of 

 this boiler was to give it such a form, that the surface 

 exposed to the fire should be great in comparison with 

 its diameter and capacity ; and this without having a 

 great surface exposed to the cold air of the atmosphere. 



The body of the boiler is in the shape of a drum. It 

 is a vertical cylinder of copper 12 inches in diameter and 

 12 inches high, closed at top and at bottom by circular 

 plates. 



In the centre of the upper plate there is a cylindrical 

 neck 6 inches in diameter and 3 inches high, shut at 

 top by a plate of copper 3 inches in diameter and 3 

 lines in thickness, fastened down by screws. 



This last plate is pierced by three holes, each about 

 5 lines in diameter. The first, which is in the centre 

 of the plate, receives a vertical tube, which conveys 

 water to the boiler from a reservoir, which is placed 

 above. This tube, which descends in the inside of the 

 boiler to within an inch above the circular plate which 

 forms its bottom, has a cock near its lower end. This 

 cock is alternately opened and shut, by means of a float- 

 er which swims on the surface of the water contained in 

 the body of the boiler. 



The second of the holes in the plate that closes the 

 neck of the boiler receives the lower end of another 

 vertical tube, which serves to convey the steam from 

 the boiler to the place where it is to be used. 



The third hole is occupied by a safety-valve. 



VOL. ii. 23 



