The Little City of Hope by F. Marion Crawford

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.