All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

302 All About Inventions movement is effected by means of pipe-lines as already explained. Some idea of the huge strides effected in this branch of the problem may be gathered from the fact that the day is not far distant when it will be possible to pump oil right across the United States from seaboard to seaboard, a distance of approxi- mately 3,500 miles. Even this method of movement is inadequate to the demand, and, as in this country, a considerable volume is moved by railway in large tank wagons and by barges. In the early days of ocean transportation the oil was packed in barrels. But this method proved wasteful owing to the amount of space which could not be occupied, such as the interstices between the circular barrels. Accordingly, it was decided to test the possibility of carrying the oil in bulk. In this instance the whole of the available freight-carrying capacity of a vessel is built in the form of large wells or tanks into which the oil is pumped through hoses, its removal being carried out in a similar manner. Not only was it found possible to carry oil in this manner and in larger paying quantities per trip, but loading and unloading were reduced to a simple, inexpensive, and rapid task. The tank steamer became recognised as the ideal vessel for carrying oil across the seas in bulk. This movement has developed to such a degree that to-day we have tankers capable of carrying 8,000 tons or more of oil as a single cargo. In addition, a barge, of similar construction and of proportionate capacity, is attached to the steamer and towed across the ocean, so that the movement of oil per trip is increased very appreciably. If we look around we can see evidences on all