I did get an invite to examine the tunnel from Alfeo Manzi and it is possible the the tunnel was later used to bring in coal. The surrounding foundation seems to predate the houses in the area and the tunnel drops into a lower basement and out to Broadway. with a stone platform, perfect for a small cannon. It was a direct line of fire at the road leading to the Kingsbridge. The bricks lining the tunnel could have been added in the later years 1880’s. we did not pull any off to examine what was underneath. If this was not used in 1776….Gunpowder may have been stored for the quarry. See for yourself in some pictures I took. One has Mr. Manzi