HOME HANDICRAFT 343
The Leyden jar is made with a glass battery jar, tinfoil, brass rods and a small piece of brass chain.
Clean the battery jar and be sure it is dry, then give it a coat of shellac, inside and out. Now cover with tinfoil set with shellac, both the inside and outside of jar, two-thirds of the way up, also the bottom, inside and outside. Make a cork for top of jar by cutting two circular pieces of wood, each 1/2 inch thick, the inner one to fit snugly within the jar, and the other to lap over the edges 1/4 inch all around. Fasten these pieces together with glue. Make a small hole in the middle of this cap and pass a quarter-inch rod through it, leaving several inches above and below the cap. To the top solder a brass ball and to the bottom fasten a small piece of chain so that several of the links rest on the tinfoil at the bottom of the jar. To charge jar use the Wimshurst Electric Machine. Connect a copper wire between one of the overhead balls on the machine and the ball at the top of the rod in the cap of the jar. Before operating the machine, place jar on glass-legged stool; by operating the machine the jar is charged.
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BY GRACE VINCENT
Most boys are wide awake and interested in whatever is going on around them. Wherever there are workmen you will always see a group of such boys watching intently, and asking questions.
When there is heavy lifting to be done and materials shifted, there must be some sort of machinery to do it. A derrick is used for that purpose. Any boy with a mechanical bent will like to make the one shown in Figure 43. This toy has the three motions used in the real thing. The mast and boom will turn, the boom and the bucket can be raised and lowered.