Rule 65 of the Federal Rules of Civil Procedure, 28 U.S. C.A., provides, (a), that a preliminary injunction shall not be issued without notice to the adverse party, and, (c), without the applicant giving security, in such sum as the court deems proper, for the payment of such costs and damages as may be incurred or suffered by any party who is found to have been wrongfully enjoined or restrained.