44 



ELECTRIC LIGHTING. 



FIG. 7. 



The thermo-electric elements are, as we have seen, arranged 

 so as to form rows, and they appear as shown in Fig. 7. The 

 negative elements, instead of being made of small elongated 

 prisms of alloy "(antimony and zinc), are re- 

 duced tolittle almost cubical blocks, 3 centi- 

 metres square by 2 deep. These little cubes 

 are connected by plates of tinned iron bent 

 like the letter Z, as in Fig. 8, and having their 

 ends soldered on the opposite faces of two 

 adjoining element?. The plates are locked 

 into the joints formed by the juxtaposition of 

 the cubes, and in order to avoid metallic 

 communication they are covered with asbestos 

 paper. The parts of these plates which are 

 soldered into the cubes are, moreover, cut so 

 as to form a kind of teeth twisted helically, 

 thus insuring good contact with the alloys to 

 which they are soldered. The construction of 

 the rows is, however, very easy, for they can be cast at a 

 single operation of any desired length. In order to do this 

 it is necessary merely to place between two cast-iron rules 

 the series of sheets of tinned irons 

 bent into the Z form, and to cast the 

 alloy over the whole; the parts of 

 the plates covered with asbestos 

 paper separate the elements without 

 further trouble. These rows, pressed 

 between the collector and the dif- 

 fuser, from which they are suitably 

 insulated by a covering of asbestos 

 paper, as shown in Fig. 9, can be connected together by their 

 free extremities, so that any desired connections and combi- 

 nations may be effected. 



Clamond has constructed two patterns of this kind of pile; 

 one, which has for some time been at work at No. 25 in the 

 Rue Saint Ambroise, lighting a workshop ; the other, which 



FIG. 8. 



