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tools changed less from the time of Herodotus to 1850 than they have since, so recent is this control. By 1868 iron bridges began to replace wooden. Now all structural iron work is made according to plans so that it can be rapidly placed and fastened.

It is hard for those of us who live in coal-burning regions to realize that the mass of humanity does not depend on it for heat. It is even harder to realize that chimneys were unknown before the twelfth century and that fireplaces when first used had very short flues, the smoke making its way to the outer air through openings in the wall just above the fire-place. Even today the brazier of coal or charcoal is characteristic of southern Europe. In 1744 Benjamin Franklin devised the castiron open heater still known by his name, while cast-iron box stoves appear by 1752 and the base-burner not until 1830. Like all other really great machines, the steamengine is a product of many ages and many inventions. One hundred and thirty years before Christ, Hero described a simple engine of no practical use and there was no advance upon his knowledge until the seventeenth century. In 1663 Edward Somerset used an engine for the purpose of raising water and the first engine of real commercial value was made in 1698 by Thomas Savery. The discoveries of Denis Papin (1690), of Thomas Newcomer (1705) and others culminated in the work of James Watt (1763). By 1802 William Symington had constructed a tug operated by an engine and in 1807 Robert Fulton made his world famed trips. In 1829 George Stephenson built the first locomotive "The Rocket" and began the operation of the first railroad, built, appropriately enough, for the hauling of coal. The turbine engines date from about 1884; the Diesel engines from 1897.

Inasmuch as the coal supply of the world is limited it becomes a matter of importance to know that it is not wasted. When we realize that some 90 per cent of the heat goes up the chimney rather than warms the house it is clear that there is great loss. The ordinary reciprocating engine utilizes only 9 per cent of the energy of the fuel, the turbine some 12 per cent, while the new Diesel engines are claimed to get 36 per cent. Many problems must be solved ere the last mentioned engines are generally available, not to speak of the problem of reducing the waste still further.

Until the development of the coal and iron industry, there had been little improvements upon the methods of control of the Romans. With the invention of power machinery comes a great series of parallel developments of which electricity is an excellent illustration.

Through all time the lightning had terrified men and stirred their imagination. Some of the simpler phenomena of electricity and magnetism were known. Franklin, in 1752, proved the identity of lightning and electric sparks. Then began one of the most wonderful series of discoveries and inventions the world has seen. To this series contributions were made by men of all the civilized races and lands. It is impossible even to list these men and their discoveries. We need only recall the electric light, telephone, telegraph, ocean cable, phonograph, kinetoscope and other machines which have almost revolutionized conditions of life.

Great electric power plants appeared after 1890 and a new group of industries developed. Aluminum, which cost before $25 a pound to produce, is now secured for a few cents. Calcium carbide from which acetylene light is made now retails at less than four cents a pound. There

has come also the present possibility of transporting power over long distances by using the electric current. Thus we may utilize water power miles from its source or burn coal, oftentimes of too low grade to justify shipment, at the mine or central plant and thus save the cost of hauling. In spite of these wonderful achievements we are in reality just starting our use of electricity.

Accompanying the development of power machinery and electricity, and to a considerable degree made possible by them, has come a wonderful advance in chemistry. This does not merely increase our power of analysis resulting in greater knowledge, but enables us to produce new things. It is synthetic.

By electrolysis an iron is now produced not much harder than aluminum which can be magnetized much more quickly than ordinary iron, and which loses its magnetism more readily, thus greatly increasing the efficiency of electromotors. Electrolytic processes are largely employed in producing nitrogen from the air, in the making of chlorates and in the recovery of the tin from old cans. Electro-chemical works are now producing rubies and sapphires identical with natural stones, save in their source. The aniline dyes obtained from the hydrocarbons contained in coal tar are so varied that the chemist claims that he can produce almost any shade of color in wool, cotton, silk or paper. Even the purple of the ancients can now be manufactured. Medicinal drugs artificially created, such as phenacetin, sulphonal, adrenalin, caffein, theobromin, tannin, camphor and atropin are on the market. The odor of the rose, violet and lily-of-the-valley can be duplicated in the laboratory. Artificial silk may yet rival the genuine. A non-inflammable celluloid (cellon) has been devised. In 1894 the fact that rubber could

exact censuses show a 50 per cent increase in the birds during the last four years." 32

After twenty-five years of agitation the government of the United States began in 1913 the control of all migratory birds, its law supplanting all state laws, determining the conditions under which they may be killed and sold. The importation of egret plumes, etc., has been prohibited. Mrs. Sage has given Marsh Island in the Gulf of Mexico to the government as a bird refuge. The success here has stimulated similar movements in Europe. Game preserves are being established by both state and national governments as well as by private citizens. It is not too much to hope that we are entering a new era in our relations to nature. The control to be discussed in the next chapter is the direction of nature's forces to produce the maximum of good to ourselves not the reckless and shortsighted display of mere brute force and the destruction of the very basis of our life.

SUGGESTIONS FOR READING

BRAUN, MAX. Animal Parasites of Man. 1906.

DARWIN, CHARLES. The Formation of Vegetable Mould Through the Action of Worms.

1881.

DRUMMOND, H. The Ascent of Man. 1894.

FABRE, J. H.
FISHER, A. K.
FORBUSH, E. H.

66

Social Life in the Insect World. 1912.

HERTER, C. A.
HORNADAY, W. T.

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Hawks and Owls of the United States. 1893.
Useful Birds and Their Protection. 1907.
Game Birds, Wild Fowl and Shore Birds. 1913.
Biological Aspects of Human Problems. 1911.
Our Vanishing Wild Life. 1912.

Wild Life Conservation in Theory and Practice. 1914. KROPOTKIN, P. Mutual Aid. 1902.

LIPMAN, J. G.

Bacteria in Relation to Country Life. 1908.

32 Bulletin, United States Department of Agriculture, No. 187.

MERRIAM, C. H.

The English Sparrow in America. 1889. Weeds of the Farm and Garden. 1911.

PAMMEL, J. H. SHELFORD, V. E. 1913.

Animal Communities in Temperate America.

SMITH, J. B. Our Insect Friends and Enemies. 1909.

THOMSON, J. A. Darwinism and Human Life. 1910.

WEED, C. M., and DEARBORN, N. Birds in Their Relations to Man (2nd Ed.). 1916.

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