Munro, John, 1849-1930 / 2008-07-04 00:00:00

We
can, however, multiply the effect by connecting a number of pairs
together, and so forming a pile or battery. Thus figure 23 shows
three couples joined "in series," the positive pole of one being
connected to the negative pole of the next. Now, if all the
junctions on the left are hot and those on the right are cool, we
will get the united effect of the whole, and the total current
will flow through the wire W, joining the extreme bars or positive
and negative poles of the battery. It must be borne in mind that
although the bismuth and antimony of this thermo-electric battery,
like the zinc and copper of the voltaic or chemico-electric
battery, are respectively positive and negative to each other, the
poles or wires attached to these metals are, on the contrary,
negative and positive. This peculiarity arises from the current
starting between the bismuth and antimony at the heated junction.
The internal resistance of a "thermo-electric pile" is, of course,
very slight, the metals being good conductors, and this fact gives
it a certain advantage over the voltaic battery. Moreover, it is
cleaner and less troublesome than the chemical battery, for it is
only necessary to keep at the required difference of temperature
between the hot and cold junctions in order to get a steady
current.
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