4. Another rule is of concerted works: the rule of the Engineer. Back of every advance in our country, in facilities of trade and transportation, or of public health and safety, stands the man who thought it out. Take, for instance, the development of the "Great American Desert." Who projected its irrigation, by which areas have been redeemed from barrenness and waste? Who planned the economic use of the Niagara Falls? Who built the Brooklyn Bridge? Who projected the vast waterway from Chicago to the Gulf? Who first thought of a cable across the depths of seas? Who bridged the Firth of Forth, the Ganges, the Mississippi? Who projected the gray docks of Montreal? the Simplon Tunnel? Who wound the iron rails across the Alleghanies, the Rockies, the Sierras? Who drew the wall that has encircled China for a thousand years? Who projected the Suez Canal? the Trans-Siberian Railway? Who sunk the mines of Eldorado? Who designed the Esplanade at Hamburg? the stone banks of the Seine? the waterways of Venice? the aqueducts of Rome? the Appian Way? the military roads of Chili and Peru? the Subway in New York? Gravity, stress, strain, weight, tension, sag, cohesion,--a few mathematical formulas, and a knowledge of the primary laws of physics,--upon such principles as these, the world is rapidly changing form and use. The Engineer, in a strange and subtle way, stands near to God. His work is done hand-in-hand with God. He takes the forces of nature and the laws of the material world, and bends them to the needs and use of man. Sky and sea or desert may be about him. He knows the arctic cold, the tropic heat; the forest and the plain; the mountain and the marsh; the brook and river; the peak and the precipice; the glacier and the tempest in their course. Out of the very elements he is daily building new paths for man to tread. Soon he, too, must pass; laid after death, it may be, beside some mighty water that his handiwork has spanned. In loneliness and silence does he not often think, I wonder, of the God with whom he deals? It is God who provides the river and the sea; God who through endless ages has piled stone on stone, crust on crust, and has crumpled the strata of the earth as tissue in His hand. It is God who has bound every mote to the earth-centre; who has sent magnetic currents coursing through the globe, and has made tides and sea-changes, and the trade-winds to blow. It is the God of the Gulf Stream, the Caribbean Sea, the God of the Appalachians, the God of the Himalayas, the God of the Cordilleras, of the Amazon, the Yukon, the Yang-tse-Kiang with which he really deals.