only pressure exerted to force the style into the wax was due to the weight of the parts.

Upon the top of A was fixed a small brass disk, and immediately over it a sensitive water jet adjusted, so that the stream of water at its sensitive part fell upon the center of the brass disk.

The Phonograph cylinder E, was rotated while words and sounds were shouted to the support to which the water jet was attached, and a record that was quite visible to the unaided eye was the result.

The tape recorder, an unusual instrument which recorded mechanically on a ³⁄16-inch strip of wax-covered paper, is one of the machines described and illustrated in U. S. patent 341214, dated May 4, 1886 (see fig. 4). The strip was coated by dipping it in a solution of beeswax and paraffine (one part white beeswax, two parts paraffine, by weight), then scraping one side clean and allowing the other side to harden.

Figure 7.—Original Plans for a Disc Graphophone Patented by Sumner Tainter in 1888, U. S. Patent 385886.

The machine of sturdy wood and metal construction, is hand powered by means of a knob fastened to the fly wheel. From the fly-wheel shaft power is transferred by a small friction wheel to a vertical shaft. At the bottom of this shaft a V-pulley transfers motion by belts to corresponding V-pulleys beneath the horizontal reels.

The wax strip passes from one 8-inch reel around the periphery of a pulley (with guide flanges) mounted above the V-pulleys on the main vertical shaft, where it comes in contact with the recording or reproducing stylus. It is then taken up on the other reel.

The sharp recording stylus, actuated by a vibrating mica diaphragm, cuts the wax from the strip. In reproducing, a dull, loosely mounted stylus, attached to a rubber diaphragm, carried sounds through an ear tube to the listener.

Both recording and reproducing heads, mounted alternately on the same two posts, could be adjusted vertically so that several records could be cut on the same ³⁄16-inch strip.

While this machine was never developed commercially, it is an interesting ancestor of the modern tape recorder, which it resembles somewhat in design. How practical it was or just why it was built we do not know. The tape is now brittle, the heavy paper reels warped, and the reproducing head missing. Otherwise, with some reconditioning, it could be put into working condition.

Most of the disc machines designed by the Volta associates had the disc mounted vertically (see figs. 5 and 6). The explanation is that in the early experiments, the turntable, with disc, was mounted on the shop lathe, along with the recording and reproducing heads. Later, when the complete models were built, most of them featured vertical turntables.

Figure 8.—Another Page of the Plans Shown in