Telephone
2 of the 7 encyclopedias on this shelf carry an entry for Telephone. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
tel'e-fon, an instrument for the transmission of sound, particularly the human voice, to a distance. The modern telephone has been developed from a simple device known for a century or two as the "lovers' telegraph." Boys make them by removing the tops from old fruit cans and connecting the bottoms by means of a string. It is well to rub the string with rosin. By talking into the mouth of one can, the vibrations are carried along the string for some distance and may be heard by holding the mouth of the second can to the ear. This rude device through which boys shouted back and forth to each other was improved by the substitution of a wire for the string and by replacing the bottoms of the cans by more delicate membranes. Prior to the invention of the telephone several thousand of these instruments were used in commercial cities as substitutes for speaking tubes. Under favorable conditions a voice could be heard at a distance of three or four miles. The honor of inventing the electric telephone does not seem to belong to any one person. As early as 1819 Charles Wheat-stone of London invented an instrument which he called the telephone, by means of which he was able to cause the music of an orchestra to be heard at a distance. Others worked on the problem of transmitting music. Elisha Gray of Chicago devised a method of transmitting sounds by electricity. The invention of the commercial telephone is credited, however, to Dr. Alexander Graham Bell of Boston. In 1874 he hit upon the idea while conducting experiments designed to make sounds visible to the deaf and dumb. Important improvements were suggested by others, notably by Thomas A. Edison. Without going into the details of construction, it may be said that the essential parts of a telephone system are a transmitter and a receiver placed in an electric circuit, as in telegraphy. One line wire, grounded at each end, is sufficient. The earth completes the circuit. This style is obsolete, however, two wires now being used, making what is called a metallic circuit. The sender of the message speaks directly into the transmitter. The voice sets in motion a delicate diaphragm. As it approaches and recedes, the vibrating diaphragm strengthens and weakens the force of an electro-magnet, causing pulsations in the electric current. The electric current strengthens and weakens an electro-magnet at the other end of the line. This second electro-magnet attracts and releases a second diaphragm, thus duplicating in the receiver the vibrations set in motion by the human voice. By holding the second diaphragm, that is to say, the receiver, to the ear, it is possible to hear the voice of the speaker miles, and we may say, even hundreds of miles, distant. Persons in Chicago and Boston converse back and forth without difficulty. Dr. Bell patented his invention. A company known as the Bell Telephone Company was incorporated and for many years maintained a monopoly. In 1893 there were about 600,000 telephones in the United States . The expiration of the principal patents has enabled independent companies to enter the field. There are now well on toward 12,000,000 instruments and 13,000,000 miles of single wire in this country and in Canada. A careful estimate for the year 1908 gives the number of telephone messages in the United States at 9,000,000,000, with a total of about 14,000,000,000 for the world. It is safe, possibly, to add twenty per cent to these figures for the year 1910. A parallel development to that going on in the United States has been going on abroad. Telephones are not cheaper of construction but are less expensive in operation than telegraph lines. They have spread all over the world. Train dispatchers are beginning to use the telephone instead of the telegraph to direct the movement of trains. In 1910 the Canadian Pacific controlled the movement of trains on 1,000 miles of track by means of the telephone. Of late they have been extended into rural communities and have done much to bring the farmer into contact with the world and within reach of the market. It is estimated that farmers' lines cost from $65 to $75 per mile, complete and ready for operation. This estimate includes two instruments per mile. Each additional subscriber adds at least $15 to the cost of the line. In districts favored by large numbers of subscribers in proportion to the length of the line, the cost of operation has been brought down to even as low as $2 a year per subscriber. In Ohio, Indiana, and Illinois, farm telephones are numerous. In regard to the Budapest news-telephone, Consul-General Paul Nash writes as follows: This system, which has been in successful operation in the capital of Hungary for several years past, is owned and managed by a private corporation, whereas the regular telephone system is owned by the government and administered by the ministry of posts and telegraphs. The annual subscription, $7.31, paid quarterly in advance, entitles the subscriber to two receivers and the full service of news, music, etc., the subscriber to pay the expenses of installation and removal, generally about $8.50. The service begins at 8:55 a.m., when a buzzing noise, loud enough to be heard across a large room and lasting for fifteen seconds, announces the correct time. At 9:30 the day's program of important events is announced; that is to say, the ceremonies, lectures, plays, races, etc. At 10 and 11 o'clock stock quotations and general news items are given. At noon comes a second announcement of the correct time, followed by parliamentary news and general items of interest. At 12:45 stock quotations from the local, Vienna, and Berlin exchanges and general news. At 2 o'clock more parliamentary and general news, and at 3 p. m. the closing prices of stocks, weather forecast, local personals, and small items, and in winter the condition of the various skating places. At 4 p. m. court and miscellaneous news. From 4:30 to 6:30 military music from one of the great cafes or gardens. In the evening the subscriber may choose between the royal opera or one of the theaters, and later music by one of the orchestras. This program is sufficiently varied to satisfy the desires of all classes of subscribers, and in general the service seems to give the utmost satisfaction. Its advantages are so manifest that no comment appears necessary. 2026 Editor's Note: When this was written the telephone still stopped at the city's edge — the first transcontinental call waited until 1915. The instrument in your pocket descends from this entry by an unbroken line; see history of the telephone . (Ed: BR 2026-07-19)
Collier's New Encyclopedia (1921)
an instrument for transmitting sounds or speech to distances where such would be inaudible through aërial sound waves. This definition excludes speaking tubes, which act simply by preserving and concentrating sound waves. Telephonic action depends on the fact that sound waves in air are capable a of communicating vibrations to stretched membrane, and if by any means such vibrations can be transmitted with true resemblance to another membrane at any distance, such receiving membrane will reproduce the sound. This capacity of a single vibrating membrane to reproduce the most complicated sounds, as of speech, is in reality the greatest mystery connected with the matter; all else relates to the mechanism of transmission only. The essential nature of the operation is weli shown in the common toy telephone sold in the streets, in which the floors of two small tin cups consist of stretched membranes, or even of paper. The two membranes are connected by a long piece of twine. If now one cup be held to the mouth and spoken into, the voice communicates vibrations to the membrane. The stretched twine communicates similar vibrations to the membrane of the other cup, and if its cavity be held to the ear the sounds will applied to the electrical telephonic apparatus so much used in modern life, but r. Such . the principle is precisely similar apparatus generally belongs to one of two main classes. The true inventor of the first telephone was undoubtedly Philip Reis, who showed, in 1861, that variations in an electric current caused by a vibrating membrane could reproduce the necessary vibrations. Reis in this way transmitted musical sounds and even words; but his apparatus was imperfect, and it was reserved for Alexander Graham Bell to perfect that which is still commonly used and known as the Bell telephone, though it is the nearly unanimous opinion of electricians that Bell's patent has been held by courts of law to cover far more ground than is really due to him, much to the public detriment and to the hindrance of progress. In Bell's telephone there is a cylindrical steel magnet, surrounded at one end by a coil of wire, whose ends are connected by wire with the circuit or line wire. It will now be understood that any change in the power of the magnet will cause currents in this wire. Near, but not touching, the magnet's end is stretched a very thin sheet of iron, as a membrane, which is spoken to through the mouthpiece. Thus made to vibrate, the iron membrane approaches to and recedes from the magnet; and as it acts toward this as an armature, tending to close the magnetic circuit, the effect is to produce fluctuating degrees of free magnetism, which again produce fluctuating or undulating currents in the line wire re. But if these fluctuating currents . are received in a precisely similar instrument, they in its coil produce variable magnetic force in the magnet, and this reproduces vibrations in the second iron membrane, which reproduce the sound. The second class of instruments are based on the microphone. If part of a galvanic current is composed of two or three pieces of matter (preferably charcoal) in loose contact, variations in the current produce variations in the conva tact pressure of the loose pieces, and the converse. Hence, instead of a vibrating membrane causing undulating currents by means of a magnet as in the Bell method, it may abut against such a series of mere contacts, and thus cause an undulating or variable current, which again is capable of converse action. A microphone is thus capable, with more or less modification, of being used as a telephone, and the employment of either method is a question of practical conditions. The Bell telephone is independent of any battery, being self-acting; but its feeble currents are incapable of transmitting speech to a distance; hence most of the modifications in magnetic telephones have had the design of increasing the power, as by using both poles of the magnet, and in other ways. The microphone, on the other hand, uses the power of a battery in its circuit, but in some respects appears less delicately sensitive than the free membrane. In practice it is very general to employ some form of microphone as the transmitting or speaking instrument, and the Bell telephone, or one of its modifications, as the receiving or hearing instrument. There are now many forms of telephone in use, the principal varieties being the bi-telephone, in which there are two receivers, one for each ear; the capillary telephone, in which electro-capillarity is used to produce telephonic effects; the chemical telephone, in which chemical or electrolytic action is utilized; the electrostatic telephone, which utilizes electrostatic disturbances in the reproduction of sound; the reaction telephone, in which two mutually reacting coils are used; and the thermo-electric telephone, in which a thermo-electric battery is used. The last-named telephone has never been used in practice. In 1892 a long-distance telephone was erected between Chicago and the larger E. cities and such service has been extended everywhere. In 1902 a patent was obtained in the United States for a wireless telephone service. De Forrest and others have since filed many patents. In 1915 the American Telegraph and Telephone Co. sent a message from Washington to Paris without wires and subsequently from Washington to Hawaii. Portable telephones were largely used in the World War. See WIRELESS TELEGRAPHY AND TELE- PHONY.