3.50 



Popular Science Monthly 



Wire-Netting Instead of Wood for 

 Surgical Splints 



ANEW kind of surgical splint in 

 which galvanized wire-netting takes 

 the place of wood, 

 has been put on the 

 market. It has 

 been tried and offers 

 many advantages. 

 The steel entering 

 into the construction 

 of this woven wire 

 splint is so tempered 

 that it can be molded 

 by hand. Being gal- 

 vanized, the wire is 

 sterilized and at the 

 same time • welded 

 into a single piece 

 that cannot fray out 

 at loose ends. As it 

 is porous, it allows a 

 certain amount of 

 evaporation and air 

 circulation to the 

 dressings beneath, 

 which wood or plas- 

 ter does not. The 



splint comes rolled like a bandage and is 

 lighter and less bulky than wooden splints. 



Two metnods of using the wire netting 

 splint are shown in the illustration 



Track Insulation Stops the Trains 

 in This Automatic Control System 



THERE are now many methods for 

 automatically stopping a train which 

 has run past a stop signal. But none is 

 simpler than the Gray-Thurber system. 

 No ramps, third rails nor other appliances 

 on the track are required. 

 The only change in the ar- 

 rangement of the track that 

 is necessary in the new sys- 

 tem is a 

 single 

 piece of in- 

 sulation, 

 placed at 

 the rail 

 joints near 

 the sema- 

 phore sig- 

 nals. 



Between 

 the insu- 

 lated rail 



ends at these joints is a make-and-break 

 relay operated by the same current as the 

 semaphore. In case of danger, the break- 

 ing of this current raises the semaphore 

 arm to the "stop" position and, at the 

 same time, it opens 

 the relay. The two 

 rail ends are there- 

 fore electrically dis- 

 connected from each 

 other. 



The valve control- 

 ling the brake is 

 normally held in- 

 operative when there 

 is a current going 

 through the valve re- 

 lay. This current 

 flows from a battery 

 on the locomotive, 

 through the locomo- 

 tive wheels, the rails, 

 the wheels of the 

 tender, and from 

 thence to the relay. 

 But when the train 

 passes a danger sig- 

 nal, the disconnected 

 rails break this cir- 

 cuit. The relay is demagnetized and a 

 spring opens the valve of the air brakes, 

 stopping the train. 



When the semaphore arm 

 goes up, the track relay opens. 

 Should the train try to pass 

 the disconnected rails, the 

 valve relay is demagnetized 

 and . the brakes are set 



The circle shows the location 

 of the valve relay which sets 

 the brakes on the train 

 when its current is shut off 



