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To screw the electrodes to the wood base, which is 3/4. thick, we’ll have to drill a hole in each electrode about 3/8” from one of the ends. Next we’ll have to make two small depressions for the pencil lead to rest in. Do this by drilling a dimple in each electrode about 1/4” from the end opposite the screw hole.      THE LOOSE-CONTACT ASSEMBLY. Lay the wood base on a flat surface, and stand the electrodes at the ends, directly facing one another. Then secure the electrodes to the base with screws. These screws will also serve as wire contacts.      Now we come to the tricky part. The pencil lead must fit between the tightened electrodes so that it is free to move slightly. If it is held firm, our loose-contact microphone won’t have a loose contact . . .consequently, it won’t work. At the same time, the fit shouldn’t be sloppy either. So do the best you can. But before you install the pencil lead, be sure to sharpen both ends on a file or fine sandpaper. Putting the Microphone Together Position the loose-contact assembly on the cigar-box as shown in the main drawing. Fasten the assembly to the box with two screws coming from inside the box. Also fasten the cigar-box to the base as shown, using the four nails. The back end of the box should extend slightly beyond the edge of the base.