pipe, A, and a 1/2-in. lock nut, B, embedded in the wood. I found that a wooden tool-rest was not satisfactory, so I had to buy one, but they are inexpensive and much handier than homemade tool rest. --Contributed by Donald Reeves, Oak Park, Ill.
When the lower half of a battery zinc becomes eaten away the remaining part can be used again by suspending it from a wire as shown in the cut. Be sure and have a good connection at the zinc binding post and cover that with melted paraffin. This prevents corrosion, which would otherwise occur from the action of the sal ammoniac or other chemical. The wire may be held at the top by twisting it around a piece
of wood or by driving a peg through the hole in the porcelain insulator. --Contributed by Louis Lauderbach, Newark, N.J.
This alarm rings so that callers approaching the door may be seen before they ring the bell and one can exercise his pleasure about admitting them.
If one has a wooden walk, the alarm is easy to fix up. Take up about 5 ft. of the walk and nail it together so as to make a trapdoor that will work easily. Place a small spring under one end to hold it up about 1/4 in. (A, Fig. 2). Nail a strip of tin along the under side of the trap near the spring and fasten another strip on the baseboard, so that they will not touch, save when a weight is on the trap. Connect up an electric bell, putting the batteries and bell anywhere desired, and using rubber-covered
[Illustration: Alarm Rings When Caller Approaches]
wire outside the house, and the alarm is complete.
When a person approaching the house steps on the trap, the bell will ring and those in the house can see who it is before the door bell rings. --Contributed by R. S. Jackson, Minneapolis, Minn.
Before proceeding to electroplate with copper, silver or other metal, clean the articles thoroughly, as the least spot of grease or dirt will prevent
the deposit from adhering. Then polish the articles and rub them over with a cloth and fine pumice powder, to roughen the surface slightly. Finally, to remove all traces of grease, dip the articles to be plated in a boiling potash solution made by dissolving 4 oz. American ash in 1-1/2 pt. of water. Do not touch the work with the hands again. To avoid touching it, hang the articles on the wires, by which they are to be suspended in the plating bath, before dipping them in the potash solution; then hold them by the wires under running water for ten minutes to completely remove every trace of the potash.