"Yellow on the low," calls the fireman again as the engine slips under still another signal bridge and finds her way to the long, unbroken sweep of the beginning of the "main." Freeman repeats the signals. For his part he is supposed to read them all the way to P----, where his run ends and the limited goes, bag and baggage, upon the rails of a connecting road. He is supposed to read, the fireman to repeat. As a practical thing it is sometimes out of the question. The cab of the big passenger puller is far from a quiet place. There is the dull pound of the drivers over the smooth rails, the roar of the great fire between them, the deafening racket of the forced draft that pours into it. The cab does not lend itself to conversation. But if Freeman does not repeat the signal indications audibly he does it mentally. It is part of his job. And the mere repeating of the signal does not assure safety. * * * * * Once, a number of years ago and upon another railroad, I rode in the cab of a fast passenger train. The road ran straight for many miles and across a level country. Each mile of its path was marked by a clock signal, gleaming against the night. The engineer shouted each of those signals, and his fireman echoed them back. "White," he would call--for white was then the safety color, not the green that has been almost universally adopted now. "White it is," would come the reply. And in another mile: "White," and "White she is." And once my heart all but leaped into my mouth. The block showed red--red, the changeless signal for danger. But our engineer did not close his throttle or reach for the handle of his air brake. "Red," he chanted in his emotionless fashion; but the fireman altering his echo to "Red she is," looked up for a moment into his chief's face. The chief never moved a muscle. Sixty seconds later he shouted again. "White." "White she is," repeated the fireman, and grinned as he thrust another shovelful of coal into the fire box. After the run was over and we sat at the comfortable eating counter of the Railroad Y.M.C.A., I asked the engineer why he had run by that red signal. He hesitated a moment. "Man alive," said he, "do you suppose I can afford to bring my train to a full stop every time one of those pesky blocks gives me the bloody eye? I could get the next two blocks and saw they were safe. I know every inch of the line, and knew that there was not an interlocking"--meaning switches and crossing tracks--"within ten miles of us. The block was out of order and I knew it. And I was right." "Suppose there was a broken rail in that block," I suggested, "wouldn't that break the current and automatically send the signal to danger?"