Sixteen Spokes and 8 Balls
This is another variant of wheel and spoke design with a few cryptic inscriptions, one of which may be the year 1899.
This design was frequently used for sewer lines, and there is an S inscribed on the outer ring, but no vents were drilled through any of the balls. So it's function is tentative.
Unknown utility dating perhaps from pre-consolidation Brooklyn.
This design is found predominately in Brooklyn, this one on Adams Street and Front in Dumbo.