Referring to the illustration: A is a five-point switch (may be homemade) ; B is a one-point switch, and C and C1 are binding posts. When switch B is closed and A is on No. 1, you have the current of one battery; when A is on No. 2 you receive the current from two batteries; when on No. 3, from three batteries; when on No. 4, from four batteries, and when on No. 5, from five batteries. More batteries may be connected to each point of switch B.
I have been using the same method for my water rheostat (homemade). I have the jars of water where the batteries are and the current coming in at a and b. --Contributed by Eugene F. Tuttle, Jr., Newark, Ohio.
Remove the paper that covers the cell and knock several good-sized holes in the zinc shell. Place the battery in a glass jar, fill it two-thirds full of strong sal ammoniac (or salt) solution and connect the terminals to whatever apparatus the current is to be used for. A few drops of sulphuric acid quickens and improves the action. The output of the cell will be nearly as great as when the battery was first bought. --Contributed by C. W. Arbitt, Austin, Texas.
There are many methods of renewing dry batteries, and I have used several of , but I found the following the best: Remove the paper cover and with a 1/4-in. drill make about six holes around the side of the zinc, about 1/2 in. from the bottom. Then drill another row of holes about half way up the side and put the battery to soak in a solution of sal ammoniac for 48 hours. Then remove and plug the holes up with hard soap, and replace in the paper box, when it will give nearly as strong a current as when new.
Not very many people realize that good, serviceable dry cells can be obtained from an automobile garage very cheap. These cells having been "run out" beyond the required number of amperes for automobile use, will give excellent service, considering their cost. Many of will give two-thirds of their original amperage. Six of such cells have been in use on my door-bell circuit for nearly a year. They can be used for other purposes just as well. --Contributed by H. H. Cutter.
Dry batteries, if not too far gone, can be renewed by simply boring a small hole through the composition on top of each carbon and pouring some strong salt water or sal ammoniac solution into the holes. This kink is sent us by a reader who says that the process will make the battery nearly as good as new if it is not too far gone beforehand.