HUMPHREY INTERNAL-COMBUSTION PUMP 271 



of the water lift. The advantage is obvious, for compression 

 pressures equal to those in modern gas engines can be employed 

 with a corresponding increase in thermal efficiency. Further, 

 by manipulating the position of pipe k, a given pump can 

 be made to meet any conditions as to height of lift, for if 

 the lift increases k can be raised so that the energy stored 

 in the air in e remains the same, there being now less air 

 but at a higher pressure. 



At this point we will indicate the method by which the 

 Humphrey system can be applied to power production. We 

 have seen that a simple modification of the pump first described 

 enables water to be put under a pressure comparable to that 

 which established practice regards as the best for use in a 

 water turbine or impulse wheel. The water is then passed 

 through an ordinary water turbine and is led back to the 

 pump to be used over and over again. Here then is a power 

 unit which in many respects is ideal. Pump and water turbine 

 work at temperatures which avoid the necessity for special 

 water-cooling devices such as are necessary in the case of gas 

 engines ; and the advantages of the water turbine, such as 

 continuous rotation, are utilised. 



The lubrication problem is reduced to such a point as to 

 be almost abolished. 



The plant can be instantly started up from " all cold " and 

 stand-by losses are therefore eliminated. The surfaces subject 

 to wear and corrosion are so slight that the depreciation of the 

 whole plant is very small. The combination can be so designed 

 also that it will be in large measure "fool proof" and can be 

 served by unskilled labour to an unusual extent. Above all, 

 even in the present experimental plant, the fuel consumption 

 is remarkably low and will undoubtedly be still further reduced 

 in the future. 



A short digression may now be made to describe an 

 important development of the arrangement shown in fig. 6, 

 which shows an apparatus wherein, at each cycle, air is 

 drawn into and rejected from the vessel e. Let us suppose k 

 is connected to a supply of combustible mixture instead of 

 opening into the atmosphere, we shall then have an automatic 

 pump for taking in a mixture and discharging it under pressure. 

 If the discharge is into a reservoir from which combustion 

 chambers a and b can be supplied, we have at once a 



