Page:Popular Science Monthly Volume 91.djvu/905

 Popular Science Monthly

German Trenches as Comfort- able as Houses

GERMAN trenches taken by the enemy have excited con- siderable comment because of the complete manner in which they are fitted up. Many of these trenches have been found to be unaffected by the heaviest bombardment. Some of the shelters taken had been ex- cavated to a depth of about forty feet. They had galleries one hun- dred and fifty yards long and seven feet high. Large rooms opened out from the galleries. Both galleries and rooms were lined with strong timber. Ventilation was afforded by oblique shafts. The exits, of which there were many, consisted of staircases. The steps were fitted with steel treads, and ramps having a gentle incline.

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���The device is nothing more than a phonograph diaphragm and a horn which amplifies the weak sounds of the relay

��Wearing Spikes on Your Feet to Prevent Slipping on Ice »

EVERYBODY knows the difficulty of maintaining a foothold when walking on ice or sleet and slush-covered streets. A device which can be worn either on shoes or rubbers to prevent slipping has been invented by C. A. Anderson and G. H. Schepstrom of Illinois. Mr. Anderson, who is a shoemaker, noticed that every winter there was a demand for creepers but that few of the creepers on the market gave satisfaction to the wearers. Not having facilities to make the steel spikes nec- essary to con- struct creepers, he called for as- sistance on his friend, Mr. Schepstrom, who is a sheet metal worker. Together they produced a type of creeper which has dis- tinct advan- tages over the ordinary kinds in use The new creepers are fastened by straps in much the same way as are some skates. There are steel studs on both the sole and the heel which enable the wearer to stand securely in any position.

���A new ice-creeper which boots or rubbers. It is

��Applying the Principle of the Phono- graph to the Telegraph Sounder

ON long telegraph lines, the current coming into a station is generally so weak that it cannot even pull down the magnet of the loud-sounding instrument. The current can, however, operate a small magnet on a very sensitive telegraph instru- ment. By making this small magnet close a heavy battery circuit in which the loud sounder is placed, the sensitive instrument acts as a relay and overcomes the difficulty. Extra batteries and instruments are therefore needed at every station. In any large size telegraph sys- tem, the ex- penses of their upkeep are con- siderable.

A very clever invention of R.A.andB. M. Grout.ofDaven- port, Iowa, does away with this expense by am- plifying the weak relay clicks directly by means of a diaphragm and horn such as are used in all phonograph instruments. The weak clicks are transmitted to the diaphragm whose vibrations act upon the air and shoot their corresponding sounds out through the horn.

��may be worn over shoes, strapped on like a skate

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