Jurisdiction is ceded to the United States of America over all lands within this state now or hereafter exclusively owned by the United States, and used as sites for post offices, custom-houses, military air bases, military installations or other public buildings: provided, that an accurate description and plan of the lands so owned and occupied, verified by the oath of some officer of the United States having knowledge of the facts, shall be filed with the secretary of this state; and, provided, further, that this cession is upon the express condition that the state of New Hampshire shall retain concurrent jurisdiction with the United States in and over all such lands, so far that all civil and criminal process issuing under the authority of this state may be executed on the said lands and in any building now or hereafter erected thereon, in the same way and with the same effect as if this statute had not been enacted; and that exclusive jurisdiction shall revert to and revest in this state whenever the lands shall cease to be the property of the United States.