“ On the twenty-fifth of July, 1879, the plaintiff, by letter, accepted the offer of a cargo of the iron, at $19.50 per ton afloat at Milwaukee; provided that the plaintiff should be allowed the deduction from the price per ton, if freight could be had for less than one dollar per ton; and also provided that the terms should be, instead of cash, a credit of four months, with interest at the rate of seven per cent. per annum after thirty days. ”

“ The complaint alleged that at the time of the breach of the contract by the defendants the market value of iron of the kind and quality agreed to be sold was much greater than the contract price of the iron, and that, if the iron had been delivered pursuant to the contract, the plaintiff could have sold it at a large profit. ”

“ The plaintiff is indebted to the defendants in the sum of six hundred and twenty-five dollars and seventy-seven cents, with interest from April 16, 1879, for the balance of the account for coal sold to the plaintiff, as stated in the ninth finding of facts, amounting, at the date of this report, to the sum of seven hundred and ninety-nine dollars, and they are entitled to have the said amount offset against the amount otherwise due from them to the plaintiff, as stated in the first conclusion of law. ”