B. M. 813
| Coordinates: | N 40.753483° W 73.981488° |
| Location: | New York
New York County Central Park Quad |
| Elevation: | 83.325 ft. |
| Type: | Chiseled Cross |
| Setting: | Stone Foundation |
| Monumented: | 1909-1912 |
| Monumented By: | NYBE+A |
| Status: | Recovered |
| Condition: | Good as of July 31, 2013 |
- Official NYBE+A Description: B. M. 813 - _West Forty-second Street._ The center of the horizontal bar of an ornamental cross with bars 1¾ inches long, near the east end of the cornerstone of the New York Public Library at West Forty-second Street and Fifth Avenue. The bench mark is on the north side of the building, is 1.33 feet west of the east side and 6.67 feet above the area. The cornerstone contains the inscription + MDCCCCII + and the cross adjacent to the letter M is the bench mark.
This is an example of an existing element being selected for use as a benchmark – and certainly one of the most unusual we’ve ever found! As noted in the description from Precise Leveling in New York City, published in 1914 (surveyed in 1909-1912) the bench mark is actually one of two cross ornaments on the library’s cornerstone.
The cornerstone contains something else interesting in addition to the bench mark: a relic box (like a time capsule) with newspapers, photos and other items relating to the creation of the library building.
As would be expected, the cross is in very good condition with no evidence of damage or reconstruction at any time in its history.
