“ In December 1956, acting under the provisions of the Miller Act, Pickard brought suit, in the name of the United States, in the United States District Court for the Middle District of Georgia against Southern and Continental for recovery of amounts allegedly owing on both the Georgia and Tennessee jobs. In January 1957, Southern filed an answer and a counterclaim in which it alleged that Southern had paid out more than the contract price on both jobs and in which recovery of the excess was sought. The $35,000 payment to Atlas was at that time included in the counterclaim. ”