Charles E. Darling, Lewiston, Me., assignor of two thirds his right
to Henry Free and John E. Lydston, of same place.--This ventilator for
windows, doors, etc., works in noiseless manner, and is watertight. It
consists of radially recessed face disks, clamped to the glass frame,
and having an intermediate pivoted disk with corresponding recesses
that are set by a crank lever and cords into open or closed piston.