Page:On the various forces of nature and their relations to each other.djvu/164

160 at the battery, see what heat we get (fig. 48). Is not that beautiful?—it is a complete bridge of power. There is metallic connection all the way round in this arrangement; and where I have inserted the platinum, which offers some resistance to the passage of the force, you see what an amount of heat is evolved,—this is the heat which the zinc would give if burnt in oxygen; but as it is being burnt in the voltaic battery, it is giving it out at this spot. I will now shorten this wire for the sake of shewing you, that the shorter the obstructing wire is, the more and more intense is the heat, until at last our platinum is fused and falls down, breaking off the circuit.

Here is another instance. I will take a