44 U. S. COAST AND GEODETIC SURVEY 



and Geodetic Survey, is 0.26 foot higher, but on account of the short- 

 ness of this series the result is not conclusive: 



Bench mark 1 (established by United States Engineers) is the top of a bronze 

 bolt in the concrete in the yard of the Engineer reservation at Lovells Island. 

 It was later reported that a pipe with screw cap had been set over the bench 

 mark to prevent its being disturbed. Elevation, 16.82 feet above United States 

 Engineers low water. 



GEORGES ISLAND 



The following bench marks are referred to the mean low water 

 as adopted by United States Engineers: 



Bench mark 3 (established by United States Engineers) consists of a lead 

 plug in a large stone on the south side of the sea wall, 36.7 feet from the angle in 

 the wall and 1.25 feet from the outer face of the same. Elevation, 13.49 feet 

 above United States Engineers low water. 



Bench mark 5a (established in 1916) is the top of an iron bolt 66.9 feet north 

 from the southwest corner of the sea wall and 4.15 feet from face of same. Ele- 

 vation, 12.93 feet above United States Engineers low water. 



Bench mark 6 (established in 1906) is top of large fiat stone alongside of an 

 iron bolt on west sea wall. It is 33.1 feet north from southwest corner of the 

 wall and 1 foot from the face of same. Elevation, 12.84 feet above United 

 States Engineers low water. 



Bench mark 6a (established in 1916) is the top of bolt described under bench 

 mark 6. Elevation, 12.90 feet above United States Engineers low water. 



Bench mark 7 (established in 1916) is a standard Coast and Geodetic Survey 

 bench mark set horizontally in the southeast corner of the red brick building at 

 inner end of wharf at Fort Warren. Elevation, 15.25 feet above United States 

 Engineers low water. 



CHELSEA CREEK ENTRANCE 



The following bench marks are referred to the Boston standard 

 datums through the primary tide station at Commonwealth Pier 

 No. 5, by a comparison of simultaneous tides consisting of 13 high 

 waters and 14 low waters observed during the period July 24 to July 

 31, 1926: 



Bench mark 1 (established in 1926) is a Coast and Geodetic Survey standard 

 disk, stamped "1/1926," set on top of the west abutment of highway bridge, 2 

 feet south of south edge of bridge. Elevation, 12.76 feet above sea-level datum; 

 17.63 feet above Boston low-water datum. 



Bench mark 2 (established in 1926) is a Coast and Geodetic Survey standard 

 disk, stamped "2/1926," set on top of the west abutment of highway bridge, 2 

 feet north of north edge of bridge. Elevation, 12.89 feet above sea-level datum; 

 17.76 feet above Boston low-water datum. 



Bench mark 3 (established in 1926) is a Coast and Geodetic Survey standard 

 disk, stamped "3/1926," set on top of east abutment of highway bridge, 18 

 inches south of south edge of bridge. Elevation, 12.84 feet above sea-level datum; 

 17.71 feet above Boston low-water datum. 



BOSTON (CHARLESTOWN) 



The following bench marks are referred directly to the Boston 

 standard datums by spirit-leveling connections: 



Bench mark 1, which has been used since the year 1846, is the top of the granite 

 wall at the entrance to the United States Navy Dry Dock No. 1 at Charlestown. 

 The point taken is directly over the inlaid bronze scale at the southerly corner 

 and outside the floating gate of the dock. Originally there was apparently no 

 special identification mark, but in 1916 a reference was made to a rectangle cut 

 in the stone. Elevation, 9.820 feet above sea-level datum; 14.69 feet above 

 Boston low-water datum. 



Bench mark 2 (established in 1867 by A. C. Mitchell), often designated as the 

 "new bench mark," is top of facing of United States Navy Dry Dock No. 1 at 

 Charlestown, on the west side and near the head directly over the foot of the 

 long steps. The place is indicated by an arrow cut in the side of the stone. 



