. . "l of the control blade,FIGS. 3, 4 and 5 are perspective views of this embodiment during operation,FIG. 6 is a side view of a second embodiment of the device,FIGS. 7 and 8 are side views of a third embodiment of the device,FIG. 9 is a perspective view of the third embodiment of the device,FIG. 10 illustrates a side view of a seat in several preferred positions.It should be noted that the components" . .