The Croton Aqueduct Department (1849-1869) was a New York City department charged with maintaining the recently opened Croton Aqueduct and eventually maintaining the resulting sewer lines and then the paving of streets made muddy with the water that the new aqueduct brought in.
The 1862 date on this cover was the earliest dated cover still seen on the streets -- up until early 2021-- when it was removed and taken to an unknown fate! It was replaced by a worn, very common, MANHATTAN DPW cover.
The circles with spokes design was a practical and attractive way to provide traction and prevent slipping on wet or icy days for both people and horses. It was a variant of an 18 spoke design used by the CAD in an 1861 dated cover now seen in Central Park(see below).
Probably it was part of the distribution system from the reservoir on 42nd St. However, this particular cover has a tangled history. It was at the midtown location seen here for only a few years before its recent removal. Images from Google Street View from 2011 show a rather nondescript cover in it's place. By November of 2017 the distinctive articulated, older cover can be seen.
There are a few "Croton Aqueduct" covers still extant (as opposed to more numerous "Croton Water" covers.) dating from 1861, 1862 , three from 1866 1866a , 1866b and 1866c and an undated cover marked CAD . The Croton Aqueduct Department was replaced at the end of 1869 by the "Boss" Tweed led Department of Public Works.
This one from 1862 was on the sidewalk of Eighth Ave just south of W 40th St. in Manhattan.