Popular Science Monthly 



485 



larger dirigible, for it loses the greater 

 lightness for the same strength of a 

 small structure. In a small dirigible 

 resistance against propulsion is so much 

 greater than the lift available for engine 

 power in the large craft, that it com- 

 pletely discounts the small craft's struc- 

 tural advantages. Any improvements in 

 lightness and strength will, therefore, 

 never make this pigmy Zeppelin a 

 superior in speed to its larger and more 

 powerful rival. 



The whole idea of a small and speedy 

 "aerial destroyer" is mistaken, since in a 

 dirigible everything has to take second 

 place to speed; otherwise Zeppelins, 



crease the lifting power, and consequent- 

 ly the size, in order to achieve greater 

 power and speed. Whether the Zeppelin 

 has been a success or not is a mooted 

 point, but the Zeppelin has been the 

 only dirigible that has accomplished 

 anything of note in this war, and the 

 smaller dirigibles have been permanently 

 relegated to their hangars. 



A Barbed-Wire-Proof Fabric 



ONE of the most trying tasks incident 

 to trench fighting has been consid- 

 erably lightened by the appearance in 

 the British trenches of gloves made of a 

 fabric which is said to be imper\ious to 



13 DRUMS OF HYDROGEN GAS 

 KEEP THE CRAFT ALOFT 



The designers believe that the laminated wood con- 

 struction will produce an airship which is one-third 

 lighter than a Zeppelin could be built with similar 

 dimensions. Two sixty-horsepower motors drive 

 four propellers, and the airship will be expected to 

 make more than seventy miles an hour at full speed 



DIRECTION 

 •RUDDER 



which cannot seek safety in landing, 

 would be at the mercy of the wind. 



The rope drive to the propellers has 

 been proved greatly inferior to bevel 

 gearing, chains and belts. The cable 

 drive was tested on the first Gross- 

 Basenach, but was quickly discarded. 



The most meritorious feature of the 

 design of the pigmy Zeppelin is in the 

 alternate heating and cooling of the gases 

 by hot vapor from the engine and cool 

 air sucked in by blowers. This certainh' 

 should i)rove of valuable assistance to 

 the dynamic lift-control without en- 

 tailing much additional weight. 



In conclusion, it seems that the idea 

 of a wooden frame has been tried, ap- 

 proximately in its present form, and 

 found lacking. The rope drive has been 

 succeeded by more efficient means of 

 power transmission, and the entire trend 

 of dirigible construction has been to in- 



barbed- wire points. The fabric is made 

 up into mittens, with the first finger and 

 thumb separate. The fabric is water- 

 proof, and in addition the gloves are 

 insulated for gripping electrically- 

 charged wires. 



The same material is applied to the 

 manufacture of sleeping-bags, which, 

 when opened, may be thrown o\er a 

 barbeJ-wire entanglement to allow a 

 soldier to climb over the sharp points 

 without injury. When made up into 

 \'ests or tunics, the fabric is strong 

 enough to turn shrapnel splinters, or 

 even a bullet when it has lost part of its 

 momentum. The interlining is anti- 

 i;epticized, so that if a bullet goes 

 through, it takes into the wound enough 

 antiseptic wool to prevent poisoning. 



The materials used in the manufacture 

 of this reniarkal)le fabric ha\e been 

 sedulously kept secret this far. 



