Tinfoil, however, is not a very satisfactory material on which to receive the vibrations in the first place.  It does not precisely respond to the movements of the marking stylus in taking the impression, and does not guide the receiving stylus sufficiently well in reproducing sounds.  Mr. Edison has therefore adopted wax in preference to it; and instead of tinfoil spread on a grooved support, he now employs a cylinder of wax to take the print of the vibrations.  Moreover, he no longer uses the same kind of diaphragm to print and receive the sounds, but employs a more delicate one for receiving them.  The marking cylinder is now kept in motion by an electric motor, instead of by hand-turning, as in the earlier instrument.

The new phonograph, which we illustrate in figure 94, is about the size of an ordinary sewing machine, and is of exquisite workmanship, the performance depending to a great extent on the perfection and fitness of the mechanism.  It consists of a horizontal spindle S, carrying at one end the wax cylinder C, on which the sonorous vibrations are to be imprinted.  Over the cylinder is supported a diaphragm or tympan T, provided with a conical mouthpiece M for speaking into.  Under the tympan there is a delicate needle or stylus, with its point projecting from the centre of the tympan downwards to the surface of the wax cylinder, so that when a person speaks into the mouthpiece, the voice vibrates the tympan and drives the point of the stylus down into the wax, making an imprint more or less deep in accordance with the vibrations of the voice.  The cylinder is kept revolving in a spiral path, at a uniform speed, by means of an electric motor E, fitted with a sensitive regulator and situated at the base of the machine.  The result is that a delicate and ridgy trace is cut in the surface of wax along a spiral line.  This is the sound record, and by substituting a finer tympan for the one used in producing it, the ridges and inequalities of the trace can be made to agitate a light stylus resting on them, and cause it to set the delicate tympan into vibrations corresponding very accurately to those of the original sounds.  The tympan employed for receiving is made of gold-beater’s skin, having a stud at its centre and a springy stylus of steel wire.  The sounds emitted by this device are almost a whisper as compared to the original ones, but they are faithful in articulation, which is the main object, and they are conveyed to the ear by means of flexible hearing-tubes.

These tympans are interchangeable at will, and the arm which carries them is also provided with a turning tool for smoothing the wax cylinder prior to its receiving the print.  The cylinders are made of different sizes, from 1 to 8 inches long and 4 inches in diameter.  The former has a storage capacity of 200 words.  The next in size has twice that, or 400 words, and so on.  Mr. Edison states that four of the large 8-inch cylinders can record all “Nicholas Nickleby,”