PASSAGE OF HEAT THROUGH FLUIDS. 357 



in height, and 1^ inch square. They are firmly fixed in the Apparatus for 

 board, at the distance of 1 1 inches asunder, and serve to flufd^''"''"*' '"^ 

 support'the two cross-pieces, DE, F G, at different heights. 



These cross-pieces are each pierced with two scjuare holes, 

 at the distance of 1 1 inches one from the other, into which 

 the upright pillars, C C, enter, and the cross-pieces are sup- 

 ported at any height that is required, by means of a screw 

 of compression. These screws are represented in the fiaure. 



The cross-piece, FG, which is represented in profile, is 17 

 inches in length, and H inch thick, and 3 inches in breadth. 

 It is pierced in the middle by a cylindrical hole of 2 inches in 

 diameter. 



The cross-piece, D E, is 17 inches in length, by H inch in 

 thickness. It is 3 inches wide at each end, and 6 inches in 

 the middle, where it is pierced by a circular hole 5 inches in 

 diameter. 



The cross-piece, D E, serves to support the annular vessel, 

 H I, of which a vertical section, passing through its axis, is 

 seen in the figure. This vessel, formed of thin brass plates, is 

 5 inches in diameter without, 3 inches in diameter within, and 

 27i inches in depth. This vessel is filled with water during 

 the experiments to the height of 2' inches ; and its form is 

 such, that ff the water that it contains were frozen into a solid 

 mass of ice, this piece of ice would have the form of a tube, 

 or perforated cylinder, of one inch in thickness and 2| inches 

 high, by 5 inches in diameter without. Its cylindricai 

 cavity would be precisely 3 inches in diameter. 



K L is a vertical and central section of a cylindrical vessel 

 of tin, of 10 inches in diameter, by 4i inches in depth. It is 

 filled with water to the height of four inches, as it is seen ia 

 the figure. 



The cross-piece, D E, is placed at such a height that the 

 bottom of the annular vessel, HI, is plunged a quarter of an 

 inch under the surface of the water contained in the great 

 cylindrical veesel, KL. 



In the axis of this last vessel is placed a small hemispherical 

 cup of wood 2 inches in diameter without, and half an inch 

 thick. It is kept in its place by a short vertical tube of tin, 

 soldered to the bottom of the cylindrical vessel, KL, into 

 which the stalk of the cup fits tightly. 



The 



