To the American people, who use six times as much petroleum per capita as the citizens of any other country, and who own ninety per cent. of the motor vehicles in operation in the world to-day, the question of future supplies is vital. In the face of an ever-increasing demand for petroleum and its products--through the many channels that have been described in this book--the ratio of production to consumption has become so altered that it is apparent that the United States must in a steadily expanding degree look to other lands for its future requirements. Statisticians and scientists differ as to how long the stores of petroleum still lying untapped in our own soil may last, but are agreed that at the present rate of consumption the American fields will have been practically exhausted before the dawn of another century and that adequate foreign reserves to supplement them must be made available by American enterprise. Petroleum is therefore a problem about which the man on the street and not merely the oil merchant must perforce think internationally. The people of other countries are to-day wide awake to the necessity of securing petroleum reserves for themselves in regions of potential oil-bearing character; and in some instances they have shown themselves very active. [Illustration: Steam stills at a modern refinery] [Illustration: Storage tank at Cushing, Oklahoma, struck by lightning--not an infrequent occurrence. 55,000 barrels of crude oil being consumed] In an exceedingly able paper presented by Mr. David White, Chief of the United States Geological Survey, to the Society of Automotive Engineers in February, 1919, that authority drew attention to “the widening angle between the flattening curve of production and the rising curve of consumption,” and announced that after a most exhaustive survey of American oil potentialities, in which many experts coöperated, the conclusions had been reached that the available oil in the ground at the end of 1918 approximated 6,740,000,000 barrels. The total production of crude from the United States wells from 1858 to the end of 1918 was approximately 4,598,000,000 barrels, more than two-thirds as much as the total remaining in the ground according to the estimates of the Mineral Resources Division of the Geological Survey. To understand fully the significance of these figures it must be realized that the rate of production has enormously increased during the past decade. Mr. White’s figures placed the oil produced from United States wells in 1918 at 345,500,000 barrels. Production, if continued on like scale annually, would exhaust the estimated supply in America in less than twenty years. Moreover, despite its vast extent, the curve of actual production in that year fell so far short of the requirements of domestic consumption that the amount of oil in storage was reduced to the extent of 27,000,000 barrels, and it was necessary to supplement