The Steadman seal lock is the name of a new lock invented by George H. STEADMAN, nephew of Judge STEADMAN of Fredericton, for fastening large mail bags. Heretofore leather straps fastened the bags with rivets and locked by ordinary padlock. The Steadman lock does the same service as the strap, padlock and ticket did. It has no key, is strong and secure and unfastened by means of an invisible spring. This lock was first used at the Fredericton Post Office in despatching mail to St. John yesterday.