THE UTILIZATION OF SUN POWER FOR IRRIGATION 

 AND OTHExt PURPOSES IN TROPICAL AGRICULTURE. 



By FRANK SHUMAN. 



IT is well known that in order to obtain the best results 

 from agriculture m most parts of the tropics, irrigation 

 is necessary, and also that in many parts of the tropics 

 coal or other fuel for doing this irrigation with mechanical 

 power is very expensive. My present purpose is to show 

 how the unlimited power of the tropical sun can be 

 utilized for irrigation and other purposes, and there is 

 surely nothing in the tropics cheaper and more plentiful 

 than sunlight. 



The rays of the sun seem at first sight to be intangible 

 and impossible to control in such a way as to utilize them 

 for practical purposes. This is not the case however. 

 They can be caught on mirrors, thrown in any desired 

 direction, absorbed and turned into useful heat by means 

 of proper contrivances. 



If the tip of an ordinary tin funnel is sawed off, the 

 inside polished, and the funnel turned towards the sun, 

 the sun's rays will be caught by this funnel and will pour 

 through the hole at the bottom just as water would, and 

 if a small blackened boiler were placed at this opening 

 they would impinge upon this, be absorbed and turned 

 into heat, which heat will turn the water in the boiler 

 into steam, and this steam would give power. This illus- 

 trates in a homely way the broad principle underlying all 

 sun-power plants. If this interesting little experiment 

 be tried it will be found impossible to hold one's hand 

 over the hole where the caught sunlight streams through, 

 because the temperature there will be considerably hotter 

 than that of boiling water. 



If a flat tin pan be painted dull b!ack on the inside, 

 covered with cotton around the bottom and sides to pre- 

 vent loss of heat, and a thin layer of water poured in, 

 covered with a pane of window glass and exposed to 



