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 and experimenters arise, all on the track of a secret, the key to which was within. And at last the modern industrial world began to have a nervous system.

So fast and free the messages began to thrill along those new fibres that the wit of the inventor was taxed to find ways of transmitting messages from wire to wire, of sending more than one message through one wire, of sending many currents indeed along every wire in a second. Speed is not only a test of fitness—it is one of the great tests in so far as the nervous system is concerned, and it is the great test of telegraph systems. And now, one and another inventor vied with one another, tripped one another up almost, in the perfecting of the apparatus for rapid transmission. One can read the story of how they brought out "combiners," "receivers," and "distributers," and how they learned to utilize all the delivery capacity of their wire, in any popular work on modern telegraphy. It is a dizzy chapter in the story of human history. And it seems, at first, as if nothing in any former chapter prepared us at all to read this one.