304 Extracts from the Journals. [April, 



for their fire represents that warmth, the absence of which ex- 

 tinguishes all organic life. 



A brief notice of the mode in which the numerical results made 

 use of have been brought out may be satisfactory, and will shew 

 that no exaggeration has been practised to the prejudice of the 

 opinion that the food of plants is organic substance. 



The area of the earth's surface is roundly estimated in square 

 miles, by multiplying the circumference into the diameter. 

 24,000+8000=zl92,000,000, area of the earth in sq. miles. 

 192,000,000 ==38,400,000, \ one-fifth part of the earth's 



) surface in square miles. 



5 

 The number of square feet in a square mile is 27,878,400; 

 whence 38,400,000+27,878,400=^1,060,520,560,000,000, the 

 number of cubic feet of soil a foot deep, in the surface of one- 

 fifth part of the area of the earth. 



A cubic foot of water weighs 1000 ounces avoirdupois; caH 

 soil twice the density of water, which is near its density; then a' 

 cubic foot of soil weighs 2000 ounces, or 125 pounds: 



] 25+1,060,520,560,000,000,= 132,564,07 1,000,000, 

 which number represents the quantity of soil in avoirdupois 

 pounds contained in one-fifth part of the earth's surface. 

 The same reduced to tons is 59,180,388,839,285. 

 Take ten per cent of this quantity as organic matter, 



5,918,038,883,928. 

 Take three-fifths of the organic matter as carbon, 



3,550,823,320,352; or there is something more 

 than three billions and a half of carbon in the soil of one-fifth 

 part of the earth's surface. 



If a thousand millions of men consume daily five ounces of 

 carbon each in respiration, they consume in a year 50,922,420 

 tons of carbon. A horse, according to Boussingault, throws off, 

 in carbonic acid, 6*07 pounds of carbon, or nearly a ton in a 

 year (-988 ton). 



The horses of Great Britain, on a moderate calculation, are 

 estimated at a million and a half;* and the inhabitants of Great 

 Britain are less than a fifth part of the human race: say, then, 

 there are fifty times as many horses in the world as in Great Bri- 

 tain, and horses alone will be found to consume every year nearly 

 75,000,000 of tons of the carbon of organic matter. 



An ox or cow converts nearly four and a half pounds of carbon 

 daily into carbonic acid. There are about three millions and a 

 quarter of cattle in Great Britain;! or the cattle of Great Britain 

 must consume more than three millions and a quarter of tons of 



•Macculloch's Statistical Account of the British Empire, vol. i. page 284. 

 t lb. page 490. 



