Government officials and employees. Executive order [stating that from 1st Saturday of June to last Saturday of September, both inclusive, of each year until further notice, 4 hours shall constitute day's work on Saturdays for all clerks and other employees of Federal Government, wherever employed, except where same conflicts with existing law, and revoking all Executive or other orders in conflict herewith, except Executive order of Apr. 4, 1908, relating to certain naval stations].