160 THE SCIENTIFIC PAPERS OF 



accordingly be the limit of the force available for moving the valve. 

 It was therefore an object of primary importance that the f rictional 

 resistance in the valve and stuffing-box should be reduced as much 

 as possible ; and this appeared to have been accomplished success- 

 fully by the construction of throttle-valve now described. If this 

 delicacy of action could be maintained, the governor would be 

 applicable no doubt to engines subjected to frequent and sudden 

 alterations of load. His own liquid governor, described at a 

 former meeting some years ago,* consisted of a cup of parabolic 

 section revolving upon a vertical spindle within a vessel partly 

 filled with oil or water ; and by the rotation of the cup, which 

 was open at top and bottom, the liquid was caused to rise up the 

 sides of the cup, but did not overflow the edge until the speed of 

 rotation had reached a certain limit. Up to the moment of the 

 cup overflowing, it acted only as a flywheel, but at the moment it 

 overflowed it became a pump, drawing in liquid through the 

 central aperture at the bottom and discharging it over the top 

 edge ; the external surface of the cup and the interior of the 

 vessel in which it revolved were provided with a series of radial 

 vanes, and the overflowing stream of liquid from the cup impinged 

 successively upon the stationary vanes and upon those on the 

 revolving cup, thus presenting a practically uniform resistance to 

 its rotation. The cup was driven by the engine through differ- 

 ential gearing, with which w y as also connected the weighted lever 

 of the throttle-valve, this constant weight acting always to main- 

 tain the uniform rotation of the cup. Although a weight was 

 thus employed both in his own and in the Allen governor, there 

 was an essential difference of action between the two, inasmuch as 

 in the Allen governor the throttle- valve had to be moved by only 

 a fractional portion of the suspended weight ; whereas in his own 

 governor the difference between the uniform rotation of the cup 

 and the varying speed of the engine acted direct upon the valve 

 through the differential gearing, the uniformly rotating cup 

 serving as a fulcrum or abutment, while the actual amount of the 

 weight upon the throttle-valve lever was immaterial, except as 

 regarded the original determination of the frictioual resistance for 

 the cup. It would thus be seen that there was indeed more simi- 



* See Proceedings of the Institution of Mechanical Engineers, 1866, p. 19 and 

 p. 112 ante. 



