After consideration of the record, the briefs and arguments of counsel we are not persuaded either that the factual findings of the District Court are clearly erroneous or that its conclusions of law thereon are unsound. The mutual obliga*615tions of General Excavating Company and John J. Driscoll Company, Inc., appellants and cross-appellants, respectively rested in part upon a formal written agreement and in part upon supplementing parol understandings between them. However, the transactions were so loosely knit and conducted that they afforded ample opportunity for the entry of ambiguities. Indeed, these measurably increased the never easy task of the trier of fact to ascertain the intent of the contracting parties. The District Judge cautiously undertook this task and, on our review, we cannot say his determinations were not right.

Affirmed.