Popular Science Montldy 



27 



The electromagnet is used with success by war surgeons to extract spHnters of steel 



which are near the surface. When used on deeply buried missiles it has been found 



to make bad wounds, because the fragment tears its way out through the flesh 



with lenses and measuring instruments 

 that are wonderfully accurate. 



In the Marindin range finder, which 

 is the type most commonly used in the 

 British infantry, an optical arrangement 

 is used, having an equivalent of two eyes 

 mounted thirty-one and a half inches 

 apart. Two reflecting prisms are em- 

 ployed, so that the rays are brought to- 

 gether in a combined beam to the eye of 

 the range officer. 



A more complicated form of range 

 finder is one equipped with magnifying 

 lenses and an adjustable prism by means 

 of which the instrument can be used for 

 rcsording distances. When the instru- 

 ment is directed towards some distant 

 object, it will be split into unmatched 

 halves until the prism is adjusted to the 

 correct angle. The distance is then in- 

 dicated on a dial. 



Range finders used on battleships are 

 fundamentally the same as the Maradin 

 finder. They differ only in details. 



The Electromagnet in War 



THE electromagnet has long been 

 used by surgeons to extract splint- 

 ers from the eye. It has not proved so 

 serviceable when its use has been extend- 

 ed to other parts of the body. In the 

 present war surgeons found that deep- 

 lying fragments of shrapnel are literally 

 torn out by the magnet, with the result 

 that gaping wounds are produced which 

 are difficult to handle. For that reason 

 army surgeons, in Germany at least, pre- 

 fer to restrict the use of the electro- 

 magnet to those cases in which the steel 

 splinters lie very near the surface. 



AX( )\ EL device which announces 

 to the cbauffeur any overheating 

 of his engine is made so that a streamer 

 is released from the radiator cap to blow 

 against the windshield. The ribbon is 

 made of a bright-colored material, and 

 shows at night as well as in the daytime. 



