46 U. S. COAST AND GEODETIC SURVEY 



Bench mark "B. & A. mileage 1.35" is at mileage 1.35 on the Boston & Albany 

 Railroad, on the northwest corner of the lower stone step at the baggage-room 

 door of the Huntington Avenue depot. A chiseled square. Elevation, 4.521 

 feet above sea-level datum; 9.39 feet above Boston low-water datum. 



Bench mark "B. & A. mileage 2.41" is on the northwest corner of the south- 

 west pier of the Boston & Albany Railroad signal bridge just east of bridge No. 

 16 at mileage 2.41. A chiseled square. Elevation, 11.417 feet above sea-level 

 datum; 16.29 feet above Boston low-water datum. 



Bench mark G2 (B. & A. mileage 3.13) is at the east end of the center support 

 of Cottage Farm bridge No. 18 carrying Commonwealth Avenue over the Boston 

 & Albany Railroad tracks at mileage 3.13, in the east face of the support, 2H feet 

 above the ground. A brass disk. Elevation, 11.001 feet above sea-level datum; 

 15.87 feet above Boston low-water datum. 



Bench mark "Van Orden Cottage Farm" (B. & A. mileage 3.13) is at th 

 east end of the foundation of the north abutment of Cottage Farm bridge No. 18 

 carrying Commonwealth Avenue over the Boston & Albany Railroad tracks at 

 mileage 3.13. A chiseled square. Elevation, 10.075 feet above sea-level datum 

 14.94 feet above Boston low-water datum. 



Bench mark "Boston & Albany Cottage Farm" (B. & A. mileage 3.13) is on 

 the west wing, south abutment, of Cottage Farm bridge No. 18 carrying Com- 

 monwealth Avenue over the Boston & Albany Railroad tracks at mileage 3.13, 

 in the northwest corner of the lower coping stone. A chiseled square. Eleva- 

 tion, 12.497 feet above sea-level datum; 17.37 feet above Boston low-water 

 datum. 



Bench mark "Cottage Farm, Boston City" (B. & A. mileage 3.13) is in line 

 with the north curb of Commonwealth Avenue and southwest of the Boston & 

 Albany Railroad tracks, near the northwest end of the top of the abutment of 

 Cottage Farm bridge No. 18 carrying Commonwealth Avenue over the railroad 

 at mileage 3.13. A point on the bridge abutment. Elevation, 27.802 feet above 

 sea-level datum; 32.67 feet above Boston low-water datum. 



SOUTH BOSTON 



The following bench marks are referred directly to the Boston 

 standard datums by spirit-leveling connections: 



Bench mark 6 (established in 1921) is a Coast and Geodetic Survey standard 

 disk cemented in window siU of fifth window on northerly side of shore end of 

 Commonwealth Pier No. 5, opposite tide staff. Stamped "6/1921." Elevation, 

 15.15 feet above sea-level datum; 20.02 feet above Boston low-water datum. 



Bench mark 7 (established in 1922) is a Coast and Geodetic Survey standard 

 disk cemented in upper surface of water table on side of heating plant opposite 

 Commonwealth Pier No. 5, stamped "7/1922." This has been adopted as the 

 primary bench mark for the tidal series at Commonwealth Pier No. 5. Elevation, 

 13.304 feet above sea-level datum; 18.17 feet above Boston low- water datum. 



Bench mark 8 (established in 1922) is a Coast and Geodetic Survey standard 

 disk, stamped "8/1922," cemented in stone retaining wall opposite stairway 

 leading down from Summer Street to C Street, and is on ledge just above first 

 landing about 7 feet below the top of wall. Elevation, 24.813 feet above sea-level 

 datum; 29.68 feet above Boston low-water datum. 



Bench mark "481 Summer Street" (established by Boston city engineers) is 

 the outer right-hand corner of granite doorstep, when facing building, of No. 481 

 Summer Street. Elevation, 21.519 feet above sea-level datum; 26.39 feet above 

 Boston low-water datum. 



Bench mark 20, or "dry dock" (established by Commonwealth of Massachu- 

 setts), is the top of brass cap on iron rod, 2 inches in diameter, which has its foot 

 in bedrock and extends upward through the concrete backing of the southern 

 wall of the Navy Dry Dock No. 3 in South Boston, nearly to the surface, and is 

 inclosed in a 4-inch iron pipe. A cast-iron cover laears the inscription "Bench 

 Mark — Do not Disturb." This bench mark was established by the Common- 

 wealth of Massachusetts and is maintained by the Navy Department. Elevation, 

 10.272 feet above sea-level datum; 15.14 feet above Boston low-water datum. 



Bench mark 9 (established in 1922) is a Coast and Geodetic Survey standard 

 disk, stamped "9/1922," set in water table on the F Street side of No. 416 West 

 Broadway, under third window, 51J^ feet from front of building. In 1922 

 building was occupied by P. F. Carey Furniture Co. Elevation, 47.480 feet above 

 sea-level datum; 52.35 feet above Boston low-water datum. 



