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The lever near the pole, on the left, opens and closes the clerestory vent panels from that point forward  (to the left).  Too open, the panel end facing the car end opens outward slightly to let fresh air come in as the car moves along. Rear facing  open panels let air escape, thereby providing ventilation in the car.   A device from before air conditioning, to be sure. 

There should be three others like it in the car, to operate vent panels to the rear (right, in the photo, as well as two levers for the clerestory vent panels on the opposite side.

Each lever moves a longitudinal rod above it that is attached each vent panel for that quarter of the clerestory.

Car 100?   BMT had this car numbered 100, a "Standard" that was rewired and modernized with a number of new features in 1960.  My guess for the 100 in your photo,  it was an IND car.

S. Islander