Having been obliged to allow the first place to America, the country which first discovered oil, and which until recently produced 70 per cent. of the world's output, Great Britain began to gain upon her by keeping command of oil-carrying ships. Whoever transports a commodity controls it, and is master of it up to a certain point, for he is the indispensable intermediary for those who wish to obtain it. Should any difficulty arise, the transporter, according as he fulfils his office or not, grants or withholds supplies for the markets, as he pleases. The British genius has always sought to compensate, by maritime superiority, for the inferiority of Great Britain in certain respects. If the United States occupied the first place among producers of oil, they ranked second to Great Britain as transporters. Great Britain, understanding that oil "is destined to play the same part in the world as coal, cotton or steel," made a special point of retaining control of oil-carrying ships. It was a thrilling duel. The world tonnage of tank-steamers rose by June 30, 1919, to 2,616,000, tons, of which 1,500,000 tons sailed under the British flag, 1,000,000 tons under the American. In June, 1920, the United States had gained the first position. They had 308 tank-steamers, amounting to 1,734,843 tons, or 51 per cent. of the whole (3,386,091 tons). On January 1, 1921, the supremacy of Great Britain was restored. Of the 524 oil-steamers afloat, 252 belonged to her, the United States having only 191. But she lost this position again six months later. Mistress of one of the foremost oil-carrying fleets, Britain next sought, until 1922, to monopolize almost all the remaining resources of the world. The _Royal Dutch-Shell_, _British Controlled Oil-fields_, and _Anglo-Persian Oil_ were valuable auxiliaries of the Foreign Office for this object. According to Dr. David White, one of the members of the American Geological Survey, this is what Great Britain possesses to-day:-- Million barrels. Canada: the whole of the deposits are reserved for British control 995 Algeria, Egypt: 50 per cent. 462.5 Persia, Mesopotamia: 75 per cent. 4,365 S.E. Russia, S.W. Siberia, Caucasus: 50 per cent. 2,925 Rumania, Galicia, Europe: 50 per cent. 1,567.5 New Russia and Sakhaline: 50 per cent. 462.5 Dutch Indies: 50 per cent. 753.75 India: the whole 995