Popular Science Monthly 



613 



To Make a Dry Battery Having 

 Lasting Qualities 



FOR the person who cares to experi- 

 ment, this type of a battery is a 

 good example to try out; for, if properly 

 constructed, it will last much longer than 

 the ordinary dry cell. The container 

 consists of a glass jar of a size suitable 

 for the battery. Coil up a cylinder of 

 heavy zinc plate to fit closely against the 

 inner surfaces of the jar and line the 



inside of the zinc 



, -.CARBON / 



ZINC CYLINDER ( 





with a good 

 grade of thick 

 blotting paper. 

 A paste is 

 made as follows: 

 For the liquid 

 mix together 3 

 parts water to 

 one part muri- 

 atic acid. (In 

 mixing acids and 

 water remember 

 to add the acid 

 to the water 

 slowly while stir- 

 ring the water.) 

 The body 

 matter for the 

 paste is made of 

 four parts powdered charcoal, 2 parts 

 flour and i part plaster of Paris. These 

 parts are measured by volume. Mix 

 this powder with the acid liquid to form 

 a paste. 



Procure a carbon from a discarded 

 cell and place it in the center of the jar, 

 then fill in around with the plaster to 

 the top of the jar and finish by sealing 

 with wax. After this stands for a few 

 hours it will be ready for use. 



A Home-made dry 

 battery cell 



Insulating the Ground Connection 

 in Radio Work 



A GOOD ground connection is of the 

 utmost importance in radio work- 

 ing. If you use the gas, steam or water 

 pipes be sure that they run out to the 

 system of mains with good electrical 

 conductivity. In some parts of the 

 country it is customary to insulate gas 

 or water pipes at the meters. Where 

 this occurs a wire shunt should be 

 connected between the house-pipes and 

 the outside mains. 



A Weight and Pulley to Adjust 

 Flexible Lamp Cords 



WHEN working around a machine it 

 is necessary to have a portable 

 light. A good way to make one is as 

 follows: An elec- 

 tric lamp is let 

 down from the 

 ceiling to the floor. 

 This wire is run 

 through a pulley 

 placed in the ceil- 

 ing as at ^. A weight B oi ]/^ 

 ^ pound is placed on the wire be- 

 " tween the pulley and the out- 

 let. A piece of tape is then wrapped on 

 the wire on the outside of and below 

 the pulley at C to keep the lamp from 

 going up out of reach. When the lamp 

 is to be used under the machine, take 

 hold of the wire above the light D and 

 pull it down. Afterwards the weight A 

 pulls the lamp up into its former place 

 again. 



To Lengthen a Shot- Chain 

 on a Pull -Socket 



THIS simple operation will prove to 

 be an economy to those handling 

 these goods. It will be found that the 

 small balls are split. These are opened 

 up with a knife-blade until the edge of a 

 cold chisel will take effect. They are 

 then further opened up to release the 

 small pin on the inside. This pin has a 

 head at each end. One ball must be 

 removed so that an extra pin may be 

 had to start the lengthening of the parts. 

 The pins are then put in to form a part 



The small balls are split and may be opened 

 up with a knife-blade and a chisel 



of the chain instead of being just a 

 fastening means. To do this properly 

 the parts are laid out on a bench, and 

 the balls clamped over the ends of the 

 pins with pliers. — E. B. Willi.\ms. 



