150 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1938 



We need scarcely remind a Washington audience that through 

 the long painstaking investigations of Dr. Abbot, Secretary of the 

 Smithsonian Institution, the amount of energy that the sun pours 

 forth has been measured with such precision that we not only know 

 the average quantity of heat and light emitted but that this average 

 varies from time to time to the extent of some 2 or 3 percent. Ex- 

 pressed in engineering language, we can say that the earth's share of 

 the sun's output is in the neighborhood of 450 million million horse- 

 power. Because of its relatively insignificant size and because also 

 of the great distance that separates the earth from the sun, a distance 

 of 93 million miles, our planet intercepts but one two-billionth of this 

 total solar output. Even so, if we stop to consider what the cost 

 to the earth would be were we charged for a year's service of heat 

 and light from the Solar Utilities Power and Light Company, we 

 would find our indebtedness mounting to staggering proportions. 

 At a price of 1% cents per kilowatt-hour, the annual budget that 

 would have to be allowed for sunshine for the United States alone 

 would aggregate a total of 327 quadrillion dollars. 



Of course such large figures as quadrillions are indeed difficult to 

 picture. If we restrict our interest for the moment to the City of 

 New York alone, we find that the cost of sunshine for Greater New 

 York for just one day amounts to 100 million dollars. 



Knowing how much of the sun's energy strikes the earth and the 

 small proportional amount which the latter intercepts, one can easily 

 calculate the total output from the Solar Power House. It is 380,000,- 

 000,000,000,000,000,000 kilowatts. The solar dynamos are evidently 

 running at full-tilt and giving continuous service. 



Life on the earth during the past, present, and future so depends 

 for its well-being upon this constant amount of sunshine that we 

 may well be interested in how long the Solar Power Company can 

 remain solvent and how long it can continue to operate while human 

 beings inhabit the earth. Meanwhile, we are impressed with the 

 apparent waste of the sun's natural resources so far as any use by man- 

 kind is concerned. Fortunately for us, millions of years ago sunshine 

 provided the energy for growing the vast tropical forests of the Car- 

 boniferous era. It is the carbon in those fallen tree trunks that we 

 are mining today in the form of coal, the chief source of fuel for our 

 own public utilities. Thus nature has stored in those primitive 

 forests buried underground unthinkable calories of canned sunshine 

 that brightens our highways and illuminates our buildings during the 

 long nights when the sun is below the horizon. So the sunshine of 

 the past is being brought literally to light again. Even the ultraviolet 

 light in our health lamps is again directly traceable to the sunshine 

 of those days when the dinosaurs roamed through the vast tropical 

 forests. 



