PopuJar Science Monthly 



831 



A Field Refrigerator for the 

 Camper or Soldier 



THE illustration shows a very ingenious 

 method adopted by a company in the 

 war zone lor storing their food su|>plies, to 

 keep them cool and out of the reach of the 

 prowling dogs. A large 

 stitutes the refriger- 

 ator, which has been'' 

 thoroughly cleaned 

 of all rot. Shehes 

 were set in and a 

 hinged door of wire 

 mesh fastened o\er 

 the opening. In this 

 case a steel door is 

 used, but the camp- 

 er can provide one 

 of slats or poles that 

 will serve his pur- 

 pose as well. 



Boy scouts will 

 find the idea attrac- 

 tive. The refrigera- 

 tor might be located 

 in some fa\'ored spot 

 in which an old tree 

 covered with iv\' 

 would be available. 

 This would elTectu- 

 ally conceal the door 

 from tramps or med- 

 dlesome marauders. 



i^ Ceutial News 



To protect edibles from wild dogs which 

 infest the district this food safe was con- 

 structed in the hollow of an old maple tree 



district. The accompanying photograph 

 shows an adaptation of the caterpillar 

 wheel — the caterpillar tread — attached to 

 an English delivery cart. 



Evidently the oc<ui)ants of the cater- 

 pillar cart are agriculliual people who live 

 in an oLitlying district where intermittent 

 rains and hea\y traf- 

 fic have played havoc 

 \vith roads. By re- 

 placing the wagon 

 wheels of the cart 

 with the tread the 

 worst roads can be 

 tra\eled over with 

 comparative ease. 

 1 he principal draw- 

 back is that tra\el 

 with the caterpillar 

 tread is slow. On 

 the other hand, the 

 horse sinks just as 

 deep in the mud as 

 he always did. If 

 the vehicle were mo- 

 tor-driven it would 

 meet all require- 

 ments. The only 

 other alternative is 

 tor some inventor to 

 find an application 

 of the caterpillar 

 tread for horseshoes. 



A Caterpillar-Tread Cart for 

 Conquering Bad Roads 



CATERPILLAR wheels are generally 

 associated with motor-driven appara- 

 tus of great weight, such as huge tractors, 

 trench diggers, army motor-truck trans- 

 ports and, of recent exploitation, the 

 "tanks" used by the British in their 

 advance against the Germans in the Somme 



ig)Ibt. Film Scr%- 



A caterpillar tread attached to an English delivery cart enables 

 it to go anywhere regardless of the condition of the roads 



Shooting Soot From Stacks With 

 Blasting Powder 



WHEN powder-plant stacks accumulate 

 enough soot to hinder the draft they 

 can be cleaned by "shooting the stack" 

 with a gun made for the purpose. This is 

 nothing more than a wooden cannon, made 

 of a piece of shafting fourteen inches long. 

 One hole is bored into the center of the 

 piece and a horizontal hole 

 is bored through the piece 

 to the bottom of the cen- 

 ter bore. This completes 

 the cannon. 



Blasting powder is 

 placed in the mouth of 

 the cannon to about two 

 inches from the top. This 

 is tamped tothecollarwith 

 dry clay, and a short fuse 

 is inserted in the touch- 

 hole. The cannon is 

 placed at the bottom of 

 the flue and the fuse is lit. 



