Society of the Cincinnati; part of lot 5, lots 42, 43, 49, and 837 in square 67.

(a) The property situated in square no. 67 in the City of Washington, District of Columbia, described as lot no. 42, as per plat recorded in the Office of the Surveyor for the District of Columbia, in liber 27 at folio 135; lot no. 43, as per plat recorded in said Surveyor’s office in liber 28 at folio 25; lot no. 49 as per plat recorded in said Surveyor’s office in liber 40 at folio 15; and part of original lot no. 5 described as follows: beginning for the same at the northeast corner of said lot and running thence west along the south line of a public alley 30 feet wide 47 and seventeen one-hundredths feet to the east line of another public alley, 30 feet wide; thence south along the east line of said alley 74 feet; thence east 47 and seventeen one-hundredths feet to the west line of a public alley 15 feet wide; thence north along the west line of said alley 74 feet to the place of beginning; occupied by the Society of the Cincinnati, a corporation of the District of Columbia, with all the buildings and improvements thereon, and the contents thereof are hereby exempt from all taxes so long as the same is so occupied and used, subject to the provisions of § 47-1002 , providing for the exemption of church and school property, subject to the proviso that said Society shall maintain therein a national museum for the custody and preservation of historical documents, relics, and archives, especially those pertaining to the American Revolution, which museum shall be accessible to the public at such reasonable hours and under such regulations as may, from time to time, be prescribed by said Society; and subject to the further proviso that if any part of said property is sold, then the exemption as to said part and said part only shall determine and if any part of said property is leased then the exemption shall cease for so long and so long only as said part is so leased. This exemption to become effective on February 24, 1938.