The other half of the Dual Contracts
This smaller sized manhole cover dates back to the "Dual Contracts" of 1913 that led to the great expansion of the New York Subway System. P.S.C was the state run Public Service Commission, that at that time was the regulator of street and under-street railways and the financial backbone of the subway expansion. The M.R.C. was the New York Municipal Railway Corporation, a corporation specifically formed to bid on a Contract to build the new subways in Manhattan Brooklyn and Queens. The MRC was owned principally by the Brookyln Rapid Transit Company, and became the BMT, the Brooklyn Manhattan Transit Company, in 1923. This cover can be dated therefore to sometime between 1913 and 1923.
The simple 3 rings of square stubs with Inscriptions top and bottom was used by the PSC for covers for both the Municipal Railway Corp and the Interborough Rapid Transit Co. the two winners of the Dual Contracts.
Probably for the distribution of DC current from generators or sub station.
PSC MRC covers are usually found close to subway lines and are a marker more specifically of the original BMT additions of the 'fourth contract". This particular cover is at Broadway and W 27th St. above the Broadway line of the BMT, today's R and W trains.