So the man and the boy “went to work to play” at building the City of Hope, for at least an hour before supper and half an hour after it, almost every day; and with the boy’s marvellous memory and the father’s skill, and the delicious profusion of fresh material which Newton kept finding in every corner of the workshop, it grew steadily, till it was a little work of art in its way.  There were the ups and downs, the crooked old roads and lanes and the straight new streets, the little wooden cottages and the big brick houses, and there was the grassy common with its trees and its tiny iron railing; and John Henry easily made posts to carry the trolley wires, which had seemed an impossible dream to the boy, beyond all realisation; and one day, when the inventor seemed farther from the tangent-balance than ever, he spent a whole afternoon in making a dozen little trolley-cars that ran on real wheels, made by sawing off little sections from a lead pencil, which is the best thing in the world for that, because the lead comes out and leaves nice round holes for the axles.  When the first car was painted red and yellow and ran up and down Main Street, guided by the wire above and only needing one little artificial push to send it either way, it looked so real that the boy was in ecstasies of delight.

“It’s worth while to be a great inventor to be able to make things like that!” he cried, and Overholt was as much pleased by the praise as an opera singer is who is called out three times before the curtain after the first act.

So the little City of Hope grew, and they both felt that Hope herself was soon coming to dwell therein, if she had not come already.

III

HOW THEY MADE BRICKS WITHOUT STRAW

But then something happened; for Overholt was tormented by the vague consciousness of a coming idea, so that he had headaches and could not sleep at night.  It flashed upon him at last one evening when Newton was in bed and he was sitting before his motor, wishing he had the thousand dollars which would surely complete it, even if he used the most expensive materials in the market.

The idea which developed suddenly in all its clearness was that he had made one of the most important parts of the machine exactly the converse of what it should be; what was on the right should have been on the left, and what was down should certainly have been up.  Then the engine would work, even if the tangent-balance were a very poor affair indeed.

The particular piece of brass casting which was the foundation of that part had been made in New York, and, owing to the necessity for its being finished very accurately and machine planed and turned, it had cost a great deal of money.  Already it had been made and spoilt three times over, and now it was perfectly clear that it must be cast over again in a reversed form.  It was quite useless to make the balance yet, for it would be of no use till the right casting was finished; it would have to be reversed too, and the tangent would apply to a reversed curve.