STEAM CHIMNEY. 139 



is of an offensive nature, it must be still more desirable to 

 dissipate, or carry it off, in the most efficacious and simple 

 manner. Mr. Webster, after various trials, has accomplished 

 thisby an ascending trunk or pipe, which communicates with 

 the chimney, and is explained in the following description, by 

 reference to fig. 4. Plate III. 



A A, the brick work surrounding the pan. 



B, the steam chimney, made of wood, about two feet 

 broad and six inches deep. A small opening at the back part 

 of the pan admits the steam into this chimney ; it may from 

 thence be carried up to the top of the building, or turned into 

 any smoke chimney near at hand. 



In order to keep the water in the pan as hot as possible 

 during the night, there are two dampers in tha steam chimney 

 at D, and if both these dampers are shut, and the whole top 

 of the pan covered closely over at c, the boiling water, even 

 when the fire is withdrawn, will keep hot for the workmen 

 till the next morning. 



C C, are loose boards, fitting close to each other, and 

 covering completely the better half of the circle of the top of 

 the pan 5 and upon this circumstance depends the whole 

 secret of getting quit of the steam. If you remove these 

 boards or partial coverings, the steam chimney loses all Its 

 use. The letter b shews the part of the top of the pan which 

 should be left open to admit to the workmen a ready com- 

 munication with the hot water ; and through this open part a 

 current of cold air is constantly seen to press and force the 

 steam rapidly up the steam chimney. 



It is proper to add, that there must always bean empty space 

 of two or three inches between the surface of the hot wate.r 

 and the under part of the cover cc } so as to permit the steam 

 to pass to the bottom of the steam chimney. To effect this 

 purpose, and at the same time to allow the copper to be 

 full of hot water, a rim or curb of wood F, about three 

 inches thick, should be fixed on the top of the copper, and 

 upon this the covering boards cc placed. This allows sufficient 

 room for the steam to press forward to the steam chimney at all 

 times. 



The cover and wood steam chimney are removeable, and may 

 serve for another copper, if both benotwantcd at the same time. 



METE- 



