There are many other easy methods of making telephones. They can be manufactured as described without waxing the string, or the boxes may be used unaltered, in which case the tin bottoms serve as drums, and the holes for the string are made in the centre of each by driving a small tack through. With these instruments the voice cannot be sent a great distance, but when only a short line is needed they succeed very well.
More complicated telephones are made with the drums of bladder and the line of soft, flexible wire. Though good and serviceable, they are more difficult to make and require more time and labor.
Speaking.
The two beef-bladders used for such a telephone must first be blown up, tied, and left about thirty hours, or until they are stretched, but not dried. When in proper condition, cut off the necks and portion of the ends, then soak them in warm water, and they will become very pliable and light in color. Having previously prepared two square pieces of board by very carefully cutting out a perfect circle in the centre of each, about as large as a medium-sized pie-pan or a tea-plate, place the bladders smoothly but not tightly over the openings, allowing the outside of the bladder to come on the bottom, and fasten it all around the circle, a little distance from the edge, with tacks so driven in that they may be easily removed.
Try the drums with your finger; if they stretch evenly they are correct, if they wrinkle, change them until they stretch perfectly smooth. Then tack a piece of firm tape securely around the edge of the circle, and cut off the bladder reaching beyond the tape. Next fasten four feet of soft, flexible wire to a large-sized gutta-percha button by threading it through the two opposite holes in the centre of the button; pass the other end of the wire through the middle of the bladder, bringing the button flat against its surface.
After attaching a weight of about seven pounds to the end of the wire, place the drum in the sun until perfectly dry. Proceed with the other in the same manner, and when both are well dried, fasten one on each end of the line and attach the drum-wires to the principal wire by loops; then stretch it firm and tight. This telephone will also need loops for supports, which should be of wire. When the instrument is carefully and properly made it will carry the voice three or four miles or more, giving every word and tone distinctly and clearly.
