MISCELLANEOUS SUBJECTS 471 



tropics where sun-power plants will be erected for the 

 present may be taken at not less than 3 per ton, the 

 saving will be as follows : 



COST OF WORKING COAL-BURNING STEAM GENERATING PLANT AS 



ABOVE. 



s. d. 



Interest and wear and tear depreciation ... 77 



163 tons of coal at ; 3 per ton ... ... ... 489 o o 



566 o a 



Sun-power steam producing plant per year ... ... ... 156 o o 



Saving ... 410 o o 



This shows that with coal at 3 per ton there is a 

 saving of 410 per annum (or nearly 52 per cent, on the 

 extra cost, 790) on the sun-power plant over that of the 

 coal-consuming plant, which would mean that in just 

 over two years the saving in fuel effected by its use would 

 wipe out the extra cost. 



Now the above figures are based on ideal conditions, 

 and we will not have these ideal conditions always in 

 actual practice. For instance, when the sun is overcast 

 with clouds, these clouds will interfere, but the margin 

 is so great that I am quite sure that even at the present 

 time sun-power plants will be very profitable in great 

 areas in the tropics, and would enormously aid the 

 development of interior countries. 



There is a splendid field for sun-power plants in entirely 

 new countries where railroads have not yet been laid 

 down, where there are no rivers, and where fuel prices 

 are therefore prohibitively high. Sun-power plants can 

 be erected here, and large areas of fertile ground made 

 cultivable by pumping water from underground. 



Wherever reasonable gravity irrigation can be used, of 

 course, we do not propose sun-power irrigation, but in 

 many cases canals, even over 100 miles long, have been 

 proposed for irrigation of new colonies, and the cost of 

 these canals may run up into the millions. 



After the canal is once built, of course, the colony 

 would have its water free except for the cost of upkeep 

 of the canal, but the interest on the huge investment 

 would go on as an expense. Now in this case, if there 

 is underground water, it would be much more profitable 

 to build at the start just enough sun-power plants to 

 supply the needs of the present small population, and 



