Popular Science Monthly 



447 



How to Rid Your Yard of Cats 



Ct)XSIUHR.\15LE aimisement may 

 be dorivfd from a tlcvice which 

 effectually rids any backyard of stray 

 cats. 



There arc many who may find it to 

 be somewhat of a comfort as well as an 

 amusement, if the number of these feline 

 nocturnal musicians in the neighborhood 

 is larger than is appreciated. 



Nail two copper wires along the top of 

 the fence, i in. apart, care being taken 

 that they do not touch. Fasten them to 

 insulated wires leading to the secondary 

 of a spark-coil in the house. Connect 

 the coil in series with si.x or more batter- 

 ies and a switch. 



When the cats appear on the fence, 

 close the switch. The effect of the 

 shock varies with the nature of the cat, 



Spark 

 CoiJ- 



Arrangement of Wires Along Fence Show- 

 ing One Battery and Switch 



but in every case the cat will move on. 

 A similar arrangement can be attached 

 to a garbage can, which must stand on 

 a dry board. The wire leading to the can 

 is insulated, and the other should be 

 grounded. — Alexander Bollerer. 



To Stop the Milk Thief 



NO one need be deprived of cream 

 for his coffee by some hungry 

 dividual who steals his milk bottle 

 from the porch. The device shown 

 here will effectively prevent any such 

 occurrence. 



The apparatus is connected with a 

 switch, bell and battery, and when any 

 one attempts to lift the milk bottle, 

 the bell is rung. 



The bottle stands upon a metal disk 

 to the center of which is joined a hea\y 

 wire, which runs through the flooring 

 where it terminates in a loop. Through 

 this loop runs a flat spring, which is 

 helfl away from a large screw by the 

 weight of the bottle. When the bottle 

 is lifted the spring raises the disk and 



touches the large screw, forming a 

 contact and giving the alarm. 



By studying the diagram it will be 

 noticed that one wire is soldered to a 

 support on which is hinged a small rod 

 insulated on one end and contacting 

 with a small L-shaped bar, through 

 which the current runs to the large 

 screw. This part of the apparatus is 

 an automatic switch. 



When it is desired to set the switch, 

 the disk on which the bottle should 

 stand is pulled up, and the lower end 

 of the wire loop bears against the small 

 rod which breaks the circuit. The 

 switch is turned on in the house. When 

 the bottle is set upon the disk the 

 contact is broken at the large screw, 

 and the small rod is forced into its 

 original position by making a contact 

 with the L-shaped bar. 



If the bottle is removed before the 

 house switch is opened, the spring rises 

 with the disk and makes a contact, but 

 owing to the play in the loop, does not 

 break the circuit through the rod. The 

 circuit can only be broken by pulling 

 the disk up farther than the spring can 

 force it. 



With this arrangement, it is absolutely 

 impossible for any one to steal the 

 bottle without your knowledge. Of 

 course, the milkman must be instructed 

 to be sure to set the bottle upon the 

 disk each day. — Ed. Gettins. 



/nsulated Tif/ ^OocH Spring 



Mechanism of the Automatic Switch for 

 Catching the Milk Thief 



