Page:Popular Science Monthly Volume 2.djvu/510

494 in Upper Egypt, yet there it yields but a poor and miserable seed, unfitted for making bread. Many ages and a prodigious expenditure 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 generations 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, pharmacy altered the use of fifty vegetable poisons, and converted them to the profit of our species. Not merely does man add a portion of utility 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, eminently mischievous, becomes indifferent to the man who is prudent and wise. Security during a storm is henceforth the price of easy and inexpensive labor.

But does man halt in so fine a path? No. Hardly has he conquered 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, furnishing us with movement, light, and heat, at pleasure.

Will you now study with me how human labor, incessantly multiplied, 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, expectation is converted into certainty, and the value of the land is farther 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,