Oil as a domestic fuel is gradually making its way because of the advantages it gives in the matter of cleanliness. Even the time-honoured oil stove has been subjected to such improvements as to be a vastly more acceptable inmate of the home than it was in days gone by. The use of petroleum as a fuel for stationary engines in manufacturing plants has also kept pace with its employment in other directions and here again its superior heating power, the elimination of dust and the saving of labour involved are economic factors of first importance. The invention of new devices for the utilization of oil have necessarily proven a stimulus to manufacture. Indeed, it would be impossible to trace the myriad paths by which petroleum enters into the public and domestic economy of the civilized world. So far we have left untouched one of its most pregnant applications; its relation to sea power and to maritime commerce, which is so wide and important as to justify a separate chapter. CHAPTER XI PETROLEUM ON THE SEVEN SEAS The intimate connection between petroleum and maritime commerce became assured from the day it was recognized that the United States had resources destined to make her the chief reservoir of the world’s supply. An interesting discourse could be written on the manner in which the people of many nations have for centuries depended on ships and seamen for light. The function of the old whaling ships in the world’s economy is now performed by the modern oil-tankers--although carrying the means of light to other lands is but a minor part of the service of these latter day vessels. The relation of petroleum to the sea may be approached from several angles. The necessity of conveying vast quantities of oil across the oceans of the world has, for instance, produced a form of maritime architecture almost as unique in its kind as is the pipe-line in land transportation. Then again, oil has within recent years tended to revolutionize the fuelling of both the merchant marine and the war fleets of this and other countries. Petroleum’s relation to naval activity in time of war is so important that it will be dealt with in a separate chapter. As a stimulus to international relations it has played a stupendous part in the evolution of the United States from a great but isolated nation into a world power.