36 WALDON FAWCETT 



ander Brown, an American. The cantilever crane is appli- 

 cable 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 shipyards and manufacturing establishments gen- 

 erally. 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 counter- 

 weight 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 counterweight at all times automatically oc- 

 cupies a similar position on the other arm. The latitude 

 of the operations of the apparatus is further broadened by 

 reason of the fact that the entire crane travels by its own 

 power up and down the track or trestle on which it is mounted. 

 A crane of this type is capable of marvelous speed. A load 

 of fourteen tons may be hoisted at a speed of 200 feet a minute ; 

 the trolley travels back and forth along the cantilever arms 

 at a speed of 600 feet a minute ; and the entire crane has suf- 

 ficient propulsive power to enable a speed of 750 feet a minute 

 in traversing the track or trestle. 



In conclusion attention must be given to the so-called 

 lifting magnet, the most wonderful of all the new appliances 

 for handhng weighty raw material. The electromagnet, 

 by the aid of electricity, performs on a large scale something 

 of the same function as the toy with which children have 

 long been familiar. One magnet will elevate a mass of metal 

 weighing two tons and it is possible to use several magnets 

 simultaneously in handling a particularly heavy steel plate 

 or bar. This plan of handling material also possesses im_- 

 mense economic advantages, inasmuch as a single mechanic 

 is usually in charge of the crane to which the magnets are 

 attached. 



