Although the refinery is self contained, the various branches of oil production, transportation and treatment have been a stimulus to many industries. Invention has been applied to the construction of improved oil drilling and pumping machinery; the pump lines themselves are prefaced by mechanical production of the requisite piping. Of the petroleum industry was born the tank steamer and the tank car. Though the crude reaches the refinery largely by means of its own transportation system, its various transformations leave by other routes. Most of the gasoline and other products that are consumed on this continent find their way from the refinery to the distributing stations in tank cars, which have become an institution on American railways. Solid trains of them leave the great refineries every day; without them it would be impossible to deliver the various petroleum products, indispensable to industry, to consumers so expeditiously as now. Petroleum’s faculty, as a standardized industry, of attracting to itself subsidiary trades is, however, but a negligible consideration in comparison with its relation to industry and commerce in the larger sense of these terms. The noted English publicist, Sydney Brooks, has drawn a pen picture of the marvellous interpenetration of the world’s industrial fabric which has taken place within the past fifty years. “To-day” says Brooks, “petroleum enters into our daily life under the guise of at least 250 different and marketable commodities. It lights our lamps and stoves; it cleans our clothes; it prepares our varnishes; it acts as a substitute for turpentine in the printing, dyeing and painting industries; it invades our tables in the form of artificial butter, confectionery and a number of other edibles; it supplies us with our wax, our candles, our chewing gum, and a vast array of ointments, salves and drugs; it furnishes the dressing table with perfumes and the smoking room with matches; it imparts the final lustre to our collars and shirts; and the textile trades use enormous quantities of it for finishing soft goods; it medicates our bodies and gives to preserved fruits their peculiarly toothsome appearance; it blends with animal and vegetable oils in a range of combinations almost infinite; its residue can be burned as coke, or used in the manufacture of electric arc-lights, or employed in road making as a rival to asphalt; it lubricates our machinery and drives our motor cars, our ships, our aeroplanes, our locomotives, our ploughs and tractors. By means of it every form of transportation on land, in the air, on the seas and below the sea, has been immeasurably extended and in many instances revolutionized. There must be at least a hundred trades that now use oil for heat and power purposes where ten or fifteen years ago they used nothing but coal. The demands for it are indeed illimitable.”