494 THE POPULAR SCIENCE MONTHLY. 



taneously in Upper Egypt, yet there it yields but a poor and miserable 

 seed, unfitted for making bread. Many ages and a prodigious expen- 

 diture of labor were required in order to develop, swell, and perfect 

 the seeds of this useful food for man. Have you ever been told that 

 wheat is distinguished from other cereals by its containing a notable 

 proportion, sometimes a quarter, of nitrogenous substances ? This 

 valuable gluten represents the blood and flesh of thousands of genera- 

 tions that perished in the culture of wheat. 



While labor supplied the most precious of its useful properties to 

 this grain, of which each of us consumes three hectolitres yearly, phar- 

 macy altered the use of fifty vegetable poisons, and converted them to 

 the profit of our species. Not merely does man add a portion of util- 

 ity to that which possesses none naturally, but he turns bad into good. 



During how many ages did the electric fluid hold a place among 

 the number of curses ! "We knew it only by the dreaded effects of 

 lightning. 



Franklin discovered the lightning-conductor, and conferred on 

 everybody the means of neutralizing this great curse. A force, emi- 

 nently mischievous, becomes indifferent to the man who is prudent and 

 Avise. Security during a storm is henceforth the price of easy and in- 

 expensive labor. 



But does man halt in so fine a path ? No. Hardly has he con- 

 quered this hostile power, than he undertakes to domesticate it. 

 Lightning, snatched from old Jupiter's hands by Franklin, becomes an 

 instrument of progress. We employ it to transmit our thoughts, to 

 reproduce our works of art, to gild our utensils, and we shall soon 

 make it perform a thousand other services. Before the lapse of half a 

 century we shall see electricity rendered more and more docile, furnish- 

 ing us with movement, light, and heat, at pleasure. 



Will you now study with me how human labor, incessantly multi- 

 plied, infinitely increases the usefulness of all our things ? 



An invisible, disregarded iron-mine renders no service to the men 

 who tread upon it. 



On the day the geologist, by the travail of his mind, divines this 

 source of useful things beneath our feet, the soil which conceals it 

 gains to some extent an increased value. 



When laborious boring has proved the existence of the mineral, ex- 

 pectation is converted into certainty, and the value of the land is far- 

 ther increased. 



The result of employing labor to work the mine is to bring to the 

 surface some tons of reddish stones containing iron. This matter is 

 not really more useful than the pebbles in the neighboring stream ; 

 yet it is more valuable, because it is known that things more profitable 

 to man can be extracted from it by labor. The mineral is treated, 

 and the crude metal, which is of greater value, is obtained. The crude 

 metal is refined, and iron is got, which is better. The iron is treated, 



