. . . "On Thursday, June 28, 1951, one of the counsel in the Dennis case accepted service on behalf of all the defendants, including petitioners, of a proposed order on mandate requiring the defendants to 'personally surrender to the United States Marshal for the Southern District of New York * * * on the 2nd day of July, 1951, at 11:05' a.m., together with a notice stating that the proposed order would" .