Scientific American, December 23, 1905, page 503:
 
THE  ELECTRICAL  SHOW  AT  THE  GARDEN.
    The annual exhibition of electrical devices and apparatus now running at Madison Square Garden was opened with great éclat on the night of December 12 last. A special wire connected the exposition with a golden key in the White House at Washington, and immediately after an address of welcome by Prof. Seaver of Columbia University, President Roosevelt, at a signal from the Garden, touched the key, lighting the numberless lamps and setting the machinery in motion. A presidential salute of twenty-one guns was thereupon fired from the Garden tower to proclaim the official opening. In many respects the exhibition this year is a disappointment. It shows very little that is really new. The theaterphone exhibited by the New York Telephone Company has probably attracted the greatest popular interest. A number of telephone receivers are connected with three New York theaters, so that visitors at the Garden can follow the conversation and music of the various performances. The theater transmitter, which is still in an experimental stage, operates on the same principle as the ordinary transmitter, except that the diaphragm is made of wood instead of metal. In this way the metallic sound of the ordinary receiver is avoided, and a much sweeter tone is secured, which is particularly noticeable in the reproduction of orchestra music. No horn is used on the transmitter, as it is desirable to avoid all false or superposed vibrations. Even in its present unfinished condition remarkable results have been obtained, and the time may soon come when one can attend any performance or concert within reach of his wire without leaving his comfortable library chair.
    A new electric elevator deserves more than passing comment. A large drum below the floor of the elevator is turned by an electric motor under control of the elevator operator. A spiral rib is formed on the face of the drum, and this engages two racks on opposite sides of the elevator shaft. Thus, the elevator feeds itself up or down according to the direction of rotation of the spiral. To relieve the friction the rack is formed with a series of rollers in place of fixed teeth. The main advantage of this system lies in the safety of the elevator; for no matter if the power should suddenly give out, the elevator will not drop, owing to the low pitch of the spiral rib. The construction also affords a considerable economy of power.
    The subject of individual motor drive of machine tools and other machinery, which is just now arousing so much interest in the mechanical world, is represented by a number of variable-speed motors, which claim high efficiency under extreme conditions. Considerable interest centers in the Poulsen telegraphone, which was described in our columns two years ago. This instrument, it will be recalled, automatically receives and records telephone messages on a steel wire. This record may be read at any time by running the wire through the transmitter of the machine. One of the oddities, though by no means a novelty, is the electric clock system, in which a single master clock operates electrically all the clocks of a building, district, or entire city. The master clock is operated by weights, and at the end of each minute sends an impulse through the circuit which correspondingly moves every clock hand in the entire system. Thus perfect accuracy is maintained. No batteries are used in the circuit, but the electrical impulse is produced inductively by the movement of an armature through a magnetic field. In this way sparking at contacts is avoided.
    The man who has not kept up-to-date on the subject of electricity in the household will find much of interest in this department of the exhibition. Complete kitchen equipments, including every variety of electrically-heated utensil from a tea kettle to a griddle, are shown. The household devices also cover a vast number of novelties ranging from sad irons, milk warmers, curling irons to electric heating pads which are used in place of hot-water bags. In contrast to these heating devices may be mentioned the small icemaking plants which are operated by electric motors. These are suitable for small stores which carry perishable goods. A number of medical apparatus and appliances are shown, such as vibrators and the like. Other features of the exhibition are wireless telegraphy, the mercury vapor light and converter, flaming-arc lamps, and various high-tension apparatus.