THATthe second section of the act entitled “An act to encourage enlistment in the regular army,” approved January twelfth, eighteen hundred and forty seven, be and the same is hereby extended to include such non commissioned officers, musicians and privates as may be recruited to fill vacancies in the first and second regiments of dragoons and the regiment of mounted riflemen ^(^and in regiments or companies of volunteers^)^ now in the service of the United States during the war with Mexico.