144 



Pn \ -SIOL OGICA L PHYSICS. 



[Chap. XIV. 



Nobili's arrangement is shown in Figs. 75 and 76. 

 It is formed of bars of antimony and bismuth, arranged 

 as in Fig. 76, so that there is a series of five couples, 

 the electromotive force of the series being the sum of 

 the electromotive forces of the five elements. There 

 are four such sets of five couples each, and they are 

 arranged in a frame, one above the other, but not 



/T^j " | 



Fig. 7t>. 



Fig. 75. 

 Thermo-Electric Pile. 



touching (Fig. 75), the bismuth of the upper one being 

 soldered to the antimony of the lower. There is thus 

 left unconnected the first antimony, which is attached 

 to a binding screw m on the frame, and forms the 

 positive pole, and the last bismuth, which forms the 

 negative pole, and is attached to n binding screw of 

 the frame. The antimony is the negative metal of 

 the two, but it forms the positive pole, because in the 

 pile the current goes from bismuth to antimony, and 

 so passes out by antimony. In the frame the various 

 elements are carefully insulated from one another. 

 By such an arrangement there is one set of junctions 

 at one end (Fig. 75), and another set at the other end. 

 By heating the junctions of one end and keeping the 

 other end normal, a current will flow through the pile, 

 if the binding screws be connected with one another. 

 Usually the pile is completely enclosed in a box of 



