Not only was there need for an immense production of mines and depth charges for ordinary uses, but the decision by the British to carry out the American Navy Department’s plans for a mine barrage across the North Sea, whose story is told in more detail in the chapter on “Working with the Allied Navies,” made necessary the production in enormous quantities of a new type of mine. Combination of the best types already in use and experiment with new features resulted in a satisfactory product of which large quantities were made and shipped abroad. All this need for high explosives caused a critical shortage and the supply of TNT, the standard charge for mines, aerial bombs and depth charges, was almost exhausted, because of the scarcity of toluol, its principal ingredient. In this menacing situation the navy’s bureau of ordnance began making exhaustive experiments which finally proved that xylol, the near chemical relative of toluol, could be used in its place. The resulting high explosive, to which was given the name TNX, proved to be the equal in every way of TNT and the building was ordered of a plant for the distillation of xylol which would make possible the production for the following year of 30,000,000 pounds of high explosives. Armament had to be furnished for merchant ships, 2,500 of them, equipment for destroyers and submarine chasers, and all the multitude of requirements for ships on distant service and for the repair ships that accompanied them. All this increase in ships and plants and personnel called for an enormous increase in the amount of materials and stores it was necessary to provide for them. The greatest total of supplies bought for the Navy in any one pre-war year amounted to $27,000,000. But the greatest total for a single day during the war amounted to $30,000,000. Among the giant tasks which the Navy undertook during the war was the building of an enormous structure in Washington for the housing of the Navy Department, of several immense storehouses, of which one in Brooklyn is said to be one of the largest storehouses in the world, the installation at Annapolis of the greatest high-power radio station yet erected, and the completion of the powerful radio plant at Pearl Harbor. The Medical Department of the Navy increased under war conditions from 327 doctors to 3,074, dentists from 30 to 485, women nurses from 160 to 1,400, and Hospital Corps members from 1,585 to 14,718. Three hospital ships were added to its equipment, it had numerous hospitals and dispensaries scattered through Great Britain and France and its hospital service at home was enlarged from 3,000 to 17,000 beds.