housing 17 supports a horizontal shaft 20 in such a manner that the shaft 20 can pivot in a horizontal plane about the vertical axis 13 but does not rotate about its own axis the blades 19 of the rotor 18 are mounted on a suitable sleeve 21 so that they can rotate about the axis of the horizontal shaft 20 each blade 19 is also supported in an inboard bearing on the sleeve 21 so that each blade can be feathered about its own axis 22 a schematic arrangement for such support is shown in fig5 a crank or arm 23 is mounted on the blade 19 and connected to a control arm 24 in such a way that the crank arm 23 may be moved through an arc 25 shown in fig5 this permits the blade 19 to be feathered as desired and such feathering can take place as the blade 19 turns about the horizontal shaft 20 thus it is seen that the blade pitch may be adjusted so that both of the blades 19 have the same pitch as desired for the appropriate existing wind conditions that is the blades may be feathered to a greater pitch when the wind velocity is low and be feathered to a lower pitch when the wind velocity is high so as to control the speed of rotation of the blades and the output of energy derived therefrom the crank 23 of each blade 19 is suitably connected so that under conditions as hereinafter described each blade may be additionally feathered during rotation about the axis 20 so that the pitch of one blade is not the same as the pitch of the other blade such condition will exist as hereinafter described when the shaft 20 is not pointing directly.