Emission and Transmission of Heat 



59 



The wheel E is driven by the vertical shaft HI provided with a 

 steadiment at L and a crank K at its upper end. The wheel G is 



loose on the fixed shaft 

 M, in which is sup- 

 ported the stem A 7 " sol- 

 dered to the surface of 

 the outer sphere, 

 which it is intended 

 to support. 



The wheel G carries 

 a horizontal ring with 

 eight spokes , each pro- 

 vided with a copper 

 plate inclined at 45; 

 at its circumference are 

 eight vertical stems 

 Q Q, bound together 

 at the top by another 

 horizontal ring; each 

 of these rods holds 

 arcs of circles R R, 

 R' R', provided with a large number of small inclined copper 

 plates, with edges almost touching the outer sphere, 

 copper cylinder fastened 

 at the upper part of the 

 outer sphere. It covers 

 three stuffing boxes 

 communicating with the 

 i n n er sphere ; through 

 one of these passes a ther- 

 mometer, through anoth- 

 er the stem of an agita- 

 tor, and the third, ordi- 

 narily closed, may re- V 

 ceive the stopper carrying the tubes designed to refill the inner 

 sphere when the level of the water has sunk. 



The outer surface of the small sphere and the inner surface 

 of the large sphere are covered with lamp black. The outer 



Fig. 168 



V 



Fig. 169 



