I saw it perfectly; much plainer, perhaps, for his putting in the clause about Abscissa.

He continued: 

“This illustration, though a slow one, leads up to a principle which may be carried to any extent.  Our first anxiety will be to spare your legs and wind.  Let us suppose that the two miles of track are perfectly straight, and make our train one platform car, a mile long, with parallel rails laid upon its top.  Put a little dummy engine on these rails, and let it run to and fro along the platform car, while the platform car is pulled along the ground track.  Catch the idea?  The dummy takes your place.  But it can run its mile much faster.  Fancy that our locomotive is strong enough to pull the platform car over the two miles in two minutes.  The dummy can attain the same speed.  When the engine reaches B in one minute, the dummy, having gone a mile a-top the platform car, reaches B also.  We have so combined the speeds of those two engines as to accomplish two miles in one minute.  Is this all we can do?  Prepare to exercise your imagination.”

I lit my pipe.

“Still two miles of straight track, between A and B. On the track a long platform car, reaching from A to within a quarter of a mile of B. We will now discard ordinary locomotives and adopt as our motive power a series of compact magnetic engines, distributed underneath the platform car, all along its length.”

“I don’t understand those magnetic engines.”

“Well, each of them consists of a great iron horseshoe, rendered alternately a magnet and not a magnet by an intermittent current of electricity from a battery, this current in its turn regulated by clock-work.  When the horseshoe is in the circuit, it is a magnet, and it pulls its clapper toward it with enormous power.  When it is out of the circuit, the next second, it is not a magnet, and it lets the clapper go.  The clapper, oscillating to and fro, imparts a rotatory motion to a fly-wheel, which transmits it to the drivers on the rails.  Such are our motors.  They are no novelty, for trial has proved them practicable.

“With a magnetic engine for every truck of wheels, we can reasonably expect to move our immense car, and to drive it along at a speed, say, of a mile a minute.

“The forward end, having but a quarter of a mile to go, will reach B in fifteen seconds.  We will call this platform car number 1.  On top of number 1 are laid rails on which another platform car, number 2, a quarter of a mile shorter than number 1, is moved in precisely the same way.  Number 2, in its turn, is surmounted by number 3, moving independently of the tiers beneath, and a quarter of a mile shorter than number 2.  Number 2 is a mile and a half long; number 3 a mile and a quarter.  Above, on successive levels, are number 4, a mile long; number 5, three quarters of a mile; number 6, half a mile; number 7, a quarter of a mile, and number 8, a short passenger car, on top of all.