638 EVERYDAY SCIENCE 



Do not put anything under the "pan" of the trap, and do not 

 put any bait inside the circle of the open jaws of the trap. Sprinkle 

 food about the traps so that the rats will be likely to step on the 

 pans when they pick it up. Cover the trap with chaff, bran, or 

 earth and sprinkle a little oil of aniseed around the traps. Be sure 

 that the trap is so fastened that the rat may drag it around a few 

 feet. Do not set the traps in the same place twice in succession. 

 These traps set in rat runways along building walls, ditch walls, 

 or at the mouths of rat burrows, or on their trails to water will catch 

 many a rat. In fact persistent use of traps will eventually rid a 

 place of rats. But remember . that it frequently requires not one 

 but many traps, and more patience and shrewdness than the rats 

 themselves have. Trapping mice is merely a matter of baiting 

 and setting the traps, but trapping rats is a test of skill. 



French cage traps can never be used with success without a period 

 of baiting. Put freshly fried bacon, cheese, grain, or any other 

 tempting bait into the trap every night for several nights and leave 

 the back door of the trap open. When the rats have become bold 

 about entering and eating, bait the trap as usual and close the back 

 door. After you have made your .catch, set the trap in another 

 place and repeat the process. 



Poisons are not safe for use in buildings or on city premises. 

 Rats are too inconsiderate about choosing a place to die. Barium 

 carbonate, mixed with egg and made into a paste with meal or 

 breadcrumbs, is a cheap and effective poison. It is also about the 

 safest poison because in small quantities it is not dangerous to 

 domestic animals. 



For fighting rats on farms, Farmers' Bulletin No. 896 offers a 

 wide range of sound advice. See also Bulletin No. 33, Biological 

 Survey, United States Department of Agriculture. 



PROJECT LVII. How to Read an Electric Meter and Compute 

 the Cost of Current, pages 486-487 



In order to understand a few terms that are used in measuring 

 electrical energy, let us liken the invisible electric current to a stream 



