Description of the Steam Pits at St. Petersburgh. 469 

 Explanations of the Sections and Ground Plan. 



A. A steam boiler, with all the usual apparatus common to 

 steam boilers, which works in general three pounds to the 

 inch, and requires heating six hours, to raise the tempera- 

 ture of the water in the cistern twenty degrees, that is, 

 from 30° to 50° of Reaumur, or from 100° to 145° of Fah- 

 renheit, which produces in the bark from 25° to 30° of 

 Reaumur, or from about 88° to 100° of Fahrenheit. I 

 have found that heating the boiler once a week is sufficient 

 to produce the above mentioned effects. 



B. The pipes for conveying the steam from the boiler into 

 the cistern, below the plants, which take a horizontal di- 

 rection above the surface of the water in the middle of the 

 pit, with perpendicular branches, at the distance of about 

 six feet apart, which convey the steam nearly to the bottom 

 of the water in the cistern. 



It should be observed that the pipes must be fixed so as to 

 allow for the expansion and contraction of the metal ; and 

 that previous to the admission of the steam from the boiler, 

 (which must not be admitted until the pressure is observed 

 to be three pounds to the inch), the small cock R, at the 

 end of the pipe B, must be opened until the steam has 

 forced its passage through. 



C. Posts sunk in the ground to support the cistern. 



D. Beams of wood fixed across the posts, to support E, 

 the bottom of the cistern, which is made of three-inch deals, 

 and caulked. 



F. Beams of wood laid horizontally on each other, and 

 fastened together with bolts and screws, and caulked, forming 

 the sides and ends of the cisterns, which are supplied at the 



