The Little City of Hope by F. Marion Crawford

It rained in New York and it "snowed slush" in Connecticut, after its manner, and the world was a very dreary place, especially all around the dilapidated cottage where everything was going to pieces, including John Henry Overholt's last hopes.

If he had been alone in the world he would have taken his small cash balance and his model to the foundry, quite careless as to whether he ever got a meal again until the Motor worked. But there was the boy to be thought of, and desperate as the unhappy inventor was, he would not starve his son as well as himself. He was quite sure of his little balance, though he had never had any head for figures of that sort. It was an easy affair in his eyes to handle the differential calculus, which will do anything, metaphorically speaking, from smashing a rock as flat and thin as a postage stamp, to regulating an astronomical clock; but to understand the complication of a pass-book and a bank account was a matter of the greatest possible difficulty. Newton would have done it much better, though he could not get to the head of his class in arithmetic. That is the difference between being an inventor and having a practical mind.