IV. RESERA'OIES OF ENERGY. 393 



entering at B, and is condensed, thus forming a vacuum, the water falling to 

 the bottom of chamber (H). To remove this water, a vacuum is alternately 

 created and destroyed, six times per minute only, in the lower chamber (G), 

 bj- alternately raising the steam or water tappet valve (the steam supplying 

 the tappet valve being reduced by reducing valve to 2| Ibs. pressure"). On 

 vacuum being created in lower chamber, the water collected in upper 

 chamber is drawn down through india-rubber foot valve (E) ; and on vacuum 

 being destroyed in lower chamber, the water falls out through the delivering 

 valve (F) into waste water cistern. 



1983. Pourneyron Turbine, |th scale, by M. Clair. 



Conservatoire des Arts et Metier '$, Paris. 



1990. Working Model of Whitelaw and Stirrat's Patent 

 Water-Mill Turbine. Glasgow Mechanics* Institution. 



The water-mill acts on a principle similar to that of the well-known 

 " Barker's mill," but the arms are bent, and otherwise shaped, so as to allow 

 the water to run from the central opening out to the jet-pipes. 



1991. Working Models of three sets of Waterwheels, viz., 

 undershot wheel, overshot wheel, and breast wheel. 



Glasgow Mechanics' Institution. 



1992. Model of Watt's Steam Engine. 



1993. Model of the High-pressure Engine. 



Prof. Meidinger, Carlsruhe. 



The models are made of sheet-metal on pasteboard, are very durable, and 

 show very clearly the relations of valve motion to piston motion. 



IV. RESERVOIRS OF ENERGY. 



1994. The First Hydraulic Press ever made. Patented by 

 Joseph Bramah, A.D. 1795, No. 2,045. 



Lent from the Patent Office Museum by the Commissioners 

 of Patents. 



1995. Weisbach's Apparatus, for illustrating experimentally 

 the laws of Hydraulics, and for the determination of hydraulic co- 

 efficients. Large reservoir for the attachment of mouth-pieces 

 and orifices under different heads. Gauging vessel. Smaller 

 reservoir for the attachment of notches and open channels. 

 Length of open channel. Collection of orifices, notches, mouth- 

 pieces, &c. Lieut.- Col. Chesney. 



BOILERS, INJECTORS, PRESSURE GAUGES, ETC. 



1969. Drawing, water-colour, on a J-inch to 1 foot scale. 

 A pair of double flue tubular Cornish boilers for high -pres- 

 sure. Adamson's patent. D. Adamson & Co.. Engineers, Hyde 

 Junction, Manchester. South Kensington Museum. 



