The honeycomb design was still very much in use when the Department of Public Works took over the building and maintenance of the sewers from the Borough Presidents in 1939. This one seated in probably an older ship's captains wheel base.
One vent hole in the center of 19 hexagons. DPW slipping in where BPB formerly sat.
The design alone says SEWER
The honeycomb design is widespread in the city, especially in Brooklyn. This sample came from Gowanus, 14th St. near 3rd Ave.