VII. REGULATORS. 469 



1998d. Governors for Turbines and Steam Engines 



(J. G. Bodemer's), with apparatus for graphic representation. 



Bock Sf Handrick, Dresden. 



1999. Model of Holt's Injection Water Regulator. 



This is an automatic valve for regulating the supply of injection 

 water admitted into steam-engine condensers, according to the 

 requirements of the vacuum. It is useful in engines having a 

 very variable load, and where water is taken from water-works 

 for condensation. Henry P. Holt, C.E. 



1999a. Series of Models of Governors, &c. for Steam 



Engines, invented by Thomas Silver, of Philadelphia. 



H.M. Commissioners of Patents. 



a. Differential marine governor. 



J>. Method of adjusting pneumatic governors Avhen in motion. 



c. Marine governor. 



d. Combined isochronal and centrifugal governor. 



e.. Model showing T. Silver's earliest attempts at combining centrifugal and 



isochronal principle in his marine governor. 

 f. Reversible link motion. 



</. Method of equalising the tension of a spring when in action. 

 h. Marine governor. 

 /'. Marine governor. 



2000. Model showing the effect of hanging the Arms of a 

 Governor from different points with respect to the axis of rota- 

 tion. Jeremiah Head, M. lust. C.E. 



By turning the horizontal sheave upon the model with gradually increasing 

 velocity, it will be seen that the cross-armed, or approximately parabolic 

 governor, goes through its range with the least variation of speed. Next in 

 efficiency is that wherein the arms are hung from the central axis, whilst the 

 very common form wherein the arms are hung externally is the least efficient, 

 or, in other words, permits the greatest variation in speed between fully open- 

 ing and fully closing the throttle -valve. 



Apparatus for feeding Steam Boilers. 



M. Cleuct, Paris. 



2001. Drawing, half the actual size, of a Regulator for a 

 25 Horse-power Boiler. M. Cleuet, Paris. 



This appliance is fixed to the inside of the furnace with an inclination of a 

 few centimetres, in such a manner that the plane of the water level proper to 

 be maintained passes through the upper tube at a point about half its length. 



Connected with the boiler, on one hand, and with the feed pipe on the 

 other, this appliance constitutes a kind of weight thermometer, the expansion 

 and contraction of which depend upon the position of the water level in the 

 boiler, and determine the flow by a discharge of the excess of water injected 

 by the feed pump, which works uninterruptedly. 



2OOla. Two ProelPs Patent Regulators for machinery, 

 and three diagrams. Dr. R. Proell, Goriitz. 



