Twine phones
The string telephones which for several years have been flooding the boulevards and the streets of the different cities of Europe, and whose invention dates back, as we have seen, to the year 1667, are very interesting apparatuses by them themselves, and we are astonished that they did not appear rather in the physics cabinets. They consist of cylindrical-conical tubes of metal or cardboard, one end of which is closed by a stretched membrane of parchment, in the center of which is fixed by a knot the string or cord intended to bring them together. When two tubes of this kind are thus joined together and that the wire is tight, as shown, it suffices for a person to apply one of these tubes against the ear and for another person to speak very close to the opening of the other tube, so that all the words spoken by the latter are immediately transmitted to the other, and one can even converse in this manner in an almost low voice.