494 



THE POPULAR SCIENCE MONTHLY, 



person consumes two pounds a day of 

 this gas, or over seven hundred pounds 

 a year, or some twenty-five tons in the 

 allotted period of seventy years; and 

 the thousand million human beings up- 

 on the eartli are all busy, day and night, 

 from birth to death, in altering tbe con- 

 stitution of the air at the same rapid 

 rate. And what man is doing, all the 

 multitudinous tribes of inferior life, in 

 the sea, on the land, and in the air, are 

 doing also. Besides this, the great op- 

 erations of combustion, fermentation, 

 and decay, upon the globe, are carried 

 on by the insatiable affinities of the 

 same ubiquitous agent. It has been 

 calculated that the oxygen required 

 daily to maintain the course of terres- 

 trial transformations is no less than 

 eight thousand million pounds, or seven 

 millions one hundred forty-two thou- 

 sand eight hundred and forty-seven 

 tons. * And, though this is probably an 

 extreme under-estimate, we have seen 

 that the stock of free oxygen in the air 

 is so vast that it would require millions 

 of years for this rate of consumption 

 to make a sensible impression upon it, 

 even if the counter-changes of the vege- 

 table kingdom, by which the balance 

 is constantly restored, should altogether 

 cease. 



Such is the grandeur of the part 

 played by this wonderful element of 

 Nature which has now been known ex- 

 actly a hundred years. In his beauti- 

 ful lecture which forms the opening 

 article of our present number. Dr. Dra- 

 per has vividly portrayed the oflSce of 

 oxygen in relation to the scheme of ter- 

 restrial life, and to this nothing needs 

 to be added. But it is fit, on the pres- 

 ent occasion, to give emphasis to the fact 

 that, up to the time of Priestley, man- 

 kind were as absolutely ignorant of 

 these things as if they had been desti- 

 tute of all capacity to understand them. 

 The human race had indeed run a vast 



1 The foregoing data are taken from Faraday's 

 "Lectures on the Non-metallic Elements."" Lon- 

 don : Longmans, 1853. 



career of intellectual activity, and had 

 exploited numberless fields of thought 

 with great results. Forms of religion 

 and systems of philosophy had grown 

 and decayed ; numerous arts were per- 

 fected and forgotten ; literatures were 

 cultivated, exhausted, and passed .by; 

 empires and civilizations had flourished 

 and faded, and for many thousands of 

 years the world's greatest minds had 

 been speculating, questioning, and in- 

 venting, before the man appeared who 

 first explained the constitution of the 

 air, and who first gave a rational an- 

 swer to the question, "What is the 

 breath of life ? " At a superficial glance 

 we should infer that there had been an 

 enormous waste of precious intellectual 

 force in all those historic ages over fu- 

 tile and worthless subjects, and that, 

 while investigating with infinite assidu- 

 ity every thing that was remote and im- 

 possible, the vital and immediate mat- 

 ters of daily and intimate concern had 

 been systematically shunned as objects 

 of study. But the intellectual evolution 

 of man has conformed to a method, and 

 i^Tature seems to have been no more eco- 

 nomical of her mental than of her mate- 

 rial resources. There is a prodigality in 

 her ways which a narrow philosophy 

 cannot comprehend. Of her profusion 

 of flowers, but few issue in fruit ; of her 

 myriads of eggs, but few are hatched ; 

 of her numerous tribes of life appear- 

 ing in the remote past, multitudes are 

 extinct; and, of the achievements of 

 her intellect, the great mass is lost in 

 oblivion. But, through all her seem- 

 ing waste, Nature has, nevertheless, a 

 grand economy. She gives the widest 

 chances, under a system which favors 

 the best; the failures are rejected and 

 the fittest survive. Through apparent- 

 ly boundless waste, with infinite de- 

 liberation, she works onward and up- 

 ward to a better state of things, and in 

 the mental world no less than in the 

 physical, through interminable defeats 

 and failures, and a prodigious amount 

 of empty and fruitless efibrt, solid and 



