“Now, gentlemen,” said Brennan, and led the way across the circle of track.

And then, from its home behind the low, powder-magazine-like sheds, there rode forth a strange car, the like of which was never seen before.  It was painted the businesslike slatyblue gray of the War Department.  It was merely a flat platform, ten feet wide by forty feet long, with a steel cab mounted on its forward end, through the windows of which one could see a young engineer in tweeds standing against a blur of moving machine-parts.

It ran on the single rail; its four wheels revolved in a line, one behind another; and it traveled with the level, flexible equilibrium of a ship moving across a dock.  It swung over the sharp curves without faltering, crossed the switch, and floated—­floated is the only word for the serene and equable quality of its movement—­round and round the quarter-mile circle.  A workman boarded it as it passed him, and sat on the edge with his legs swinging, and its level was unaltered.  It was wonderful beyond words to see.  It seemed to abolish the very principle of gravitation; it contradicted calmly one’s most familiar instincts.

Every one knows the sense one gains at times while watching an ingenious machine at its work—­a sense of being in the presence of a living and conscious thing, with more than the industry, the pertinacity, the dexterity, of a man.  There was a moment, while watching Brennan’s car, when one had to summon an effort of reason to do away with this sense of life; it answered each movement of the men on board and each inequality in the makeshift track with an adjustment of balance irresistibly suggestive of consciousness.  It was an illustration of that troublous theorem which advances that consciousness is no more than the co-relation of the parts of the brain, and that a machine adapted to its work is as conscious in its own sphere as a mind is in its sphere.

The car backed round the track, crossed to the straight line, and halted to take us aboard.  There were about forty of us, yet it took up our unequally distributed weight without disturbance.  The young engineer threw over his lever, and we ran down the line.  The movement was as “sweet” and equable as the movement of a powerful automobile running slowly on a smooth road; there was an utter absence of those jars and small lateral shocks that are inseparable from a car running on a double track.  We passed beyond the sheds and slid along a narrow spit of land thrusting out into the mud-flanked estuary.  Men on lighters and a working-party of bluejackets turned to stare at the incredible machine with its load.  Then back again, three times round the circle, and in and out among the curves, always with that unchanging stateliness of gait.  As we spun round the circle, she leaned inward like a cyclist against the centrifugal pull.  She needs no banking of the track to keep her on the rail.  A line of rails to travel on, and ground that will carry her weight—­she asks no more.  With these and a clear road ahead, she is to abolish distance and revise the world’s schedules of time.