Early Brooklyn Power
The Edison Electric Illuminating Co of Brooklyn was founded in 1887, and It was merged with it's rival the Kings County Electric Light and Power Co. to form Brooklyn Edison in 1919. By that time the company had extended power to customers in most of the borough. The KCEL&P by then had built some of the largest generators (AC) in the US, including the Gold Street Generator near the Brooklyn Navy Yard. not far from the location of this rectanglular cover.
During its 32 year run the EEI Brooklyn installed thousands of manholes. The covers were generally square or rectangular, with variations of the two-stranded basket weave pattern, often with rings or squares of vent holes, and usually with "E E I Co" in a badge at the center. Note also the careful triangular borders on the lid and on the rim of the cover seat, which may be an indicator of the covers being of a earlier vintage than the plain seats seen further out. (see below)
The early EEI Co covers generally were sites where the AC current from the generators was converted to DC currant. Today they are probably transformer sites leading to consumer lines.
This cover is on Jay St. and Cathedral Place. There are numerous examples of similar covers across the borough.