Modern drawbridges across rivers, canals, the entrances of docks, etc., are generally made to open vertically, and the movable portion is called a bascule, balance or lifting bridge; a turning, swivel or swing bridge; or a rolling bridge, in accordance with the mode in which it is made to open. Swing bridges are usually divided into two parts meeting in the middle, and each moved on pivots on the opposite sides of the channel, or they may move as a whole on a pivot in the middle of the channel. Rolling bridges are suspended from a structure high above the water, and are propelled backwards and forwards by means of rollers. [Illustration: BASCULE BRIDGE OPEN[53]] [Illustration: BASCULE BRIDGE CLOSED[53] The advantages of this type of bridge are that the entire width of the channel is available for navigation, and the draw may be opened and closed more readily than the swing type.] The Story of a Deep Sea Monster[54] The early day was blue and silver; one of those colorful mornings peculiar to southern Florida. Sandwiched between the earth and the turquoise sky, the Atlantic lay gleaming like a huge silver wafer in the sunlight. Not the faintest suggestion of a ripple marred its shining surface. Suddenly out of the stillness of the silver water a huge black fin was lifted, and a little group of men lounging on the deck of an idle fishing craft drew near the rail and used their glasses. “Shark,” remarked the captain pleasantly after a moment’s scrutiny. “Who wants to go out with me for a little fun?” The hastily lowered lifeboat pointed a slim nose toward the large black shape thrashing about in the shallow water. Three men were in the boat--Captain Charles H. Thompson of the yacht “Samoa,” one of the yacht’s crew, and a winter visitor to southern Florida. As they drew near, the sailor took one look at the gigantic creature and yelled to the captain: “For heaven’s sake, man, don’t harpoon that thing; we will be crushed like an egg shell!” Poised in the bow of the boat, harpoon in hand, stood the captain, and as they drew alongside there was a flash; the steel glittered for a moment in the sunlight, then sank into the huge black bulk. Simultaneously the little boat spun around and shot out toward the Gulf Stream like an agitated and very erratic rocket, flinging great sheets of spray high into the air as it sped. Thus began a thirty-nine hours’ ride filled with wildest thrills, during which time Captain Thompson battled with the fish, the sailor bailed the boat unceasingly, lest they be swamped, and the tourist raised an anxious and eloquent voice to high heaven. The men were without food the entire time, sharing only a small bottle of water among them.