Page:Popular Science Monthly Volume 62.djvu/80

74 curve, resuming the normal rate of travel when the dangerous point has been passed.

The part which cranes of various kinds have played in the solution of the problem of the economical handling of raw material of various kinds is indeed an important one and there has been a steady increase in capabilities until there are now in service in the United States a number of cranes each of which is capable of handling a load of one hundred tons.

Easily the most remarkable of all the cranes yet constructed are the great balanced cantilevers invented by Alexander Brown, an American. The cantilever crane is applicable to a large range of work and is the

most perfect machine yet devised for use in handling armor plate and other heavy parts in ship-yards and manufacturing establishments generally. The cantilever is divided into two arms, which in some instances have a span of over 350 feet. By means of trolley and hoist block, mounted on the cantilever of the crane, the load can be hoisted from the ground and traversed from one end of the cantilever to the other, the pier or base of the crane being so arranged that the load passes through it. These cantilever cranes have an automatic counterweight running on a track along the bridge and above the hoisting trolley, and connected by ropes to the latter, so that whatever the position of the hoisting trolley on one arm of the crane, the