470 Description of the Steam Pits at St. Petersburgh. 



end of the pit through a pipe and funnel S, wherein are 

 placed a thermometer and gage for ascertaining as near as 

 possible, the heat, as well as the depth of the water. The 

 cisterns are covered with a second floor G (perforated only 

 where it is over the water) made also of three-inch deals ; 

 this floor is covered with fascines H, to the depth shewn in 

 the Sections. 



I. Tanner's bark, sand, or earth in which the plants are 

 plunged. 



K. Reservoir, supplying the boiler with water, filled from 

 a well Y, in the steam-house, by a small forcing pump. 



Remarks. — The cisterns have a small inclination towards 

 the middle of the house, under which part is a drain L, the 

 use of which is first, to carry off the water from the cisterns (or 

 likewise from the boiler), through the pipes M, when it is ne- 

 cessary to change it : secondly, to introduce and form a current 

 of cold air when wanted below the tan, admitted through the 

 tube N, which is opened and shut as required by the damper 

 at d. This current, which forces the hot air to the opposite 

 end, is let out by means of a ventilator T, which is an iron 

 pipe covered with a cap, to open occasionally, and forms an 

 agreeable moist air in the house ; and, thirdly, for conducting 

 the atmospheric air into the iron tube O, wherein it is heated 

 by the action of the fire, at the time the flues are lighting, 

 and is conveyed to the end of the house, where it escapes at 

 P. W is the front flue, wherei*. the iron tube O is heated by 

 the fire, which is at V; after the flue has been some time 

 lighted, the tube is shut by means of a damper at Z. This 

 operation not only affords a pleasant succession of heated 

 atmospheric air, but heat is at the same time gained, which 



