165,748. La Cierva y Codorniu, J. de. July 1, 1920, [Convention date]. Void [Published under Sect. 91 of the Act]. Screw and like propellers.-The pitch of each blade of an aerial propeller may be varied as shown in Figs. 3 and 4, where the blade 14 is carried by a rigid spar 15 which is secured to a rotatable sleeve 16. Variation of pitch is effected by axial movement of a shaft 20 through a member 18, or by rotation of the spar 15.