MISCELLANEOUS SUBJECTS 465 



ordinary engineer can run it and that its wear and tear 

 will be reasonable, and further, that excessive labour will 

 not be required to handle it, then also there is nothing 

 in it. 



These are important factors to consider. Therefore it 

 is necessary for me to give definitely the cost of con- 

 struction, maintenance, and labour, and to show definitely 

 that sun-power can be properly produced throughout 

 those vast areas of the inland tropics where coal is very 

 expensive. 



Sun-power plants need not compete with coal for the 

 present at any of those tropical places near the coast 

 where coal is reasonably cheap. At present we can con- 

 fine our work to where the sun is at its best, and where 

 coal is very expensive, from, say, 2 to 3 a ton. These 

 prices of coal obtain throughout very large areas in the 

 inland tropics areas which, given plenty of mechanical 

 power for irrigation, can be made to support large popu- 

 lations. Finally, when coal and oil are used up we shall 

 all have to come to sun power, but by that time we shall 

 know much that we do not know now, and will particu- 

 larly know how to transport " sun power " from the 

 tropics to the temperate zones. 



The value of our work consists in generating steam 

 for power purposes with the heat obtained by the sun's 

 rays. " Sun steam " is exactly the same thing as steam 

 generated by burning coal under a boiler, and can be 

 used for any desired purpose and in any desired manner 

 in which ordinary steam can be used. It can be used for 

 driving reciprocating engines or turbines, for irrigation, 

 or for the running of factories. In fact, for anything 

 whatever where power is required. It is, therefore, not 

 necessary to describe except in a general way the engine 

 and pump end of this sun-power plant. The engine is 

 a low-pressure reciprocating condensing engine, and the 

 pump an ordinary reciprocating pump, which, in this 

 instance, was used for pumping water out of the Nile as 

 an exhibition of its power. 



Experience has shown us that steam at atmospheric 

 pressure (14*7 Ib. absolute) gives the greatest return in 

 power per pound sterling invested. If we attempt to- 



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