Telephone switchboard

“ Telephones that are not dial-operated are connected with manual central offices, where operators seated at switchboards make the connections by hand. Switchboards differ greatly in size. In small villages one or two operators handle all calls. In large cities the volume of calls requires hundreds of operators working at large multiple switchboards. The term multiple comes from the fact that the end of each subscriber’s telephone line is duplicated or multipled at intervals throughout the switchboard. For example, a switchboard serving 6,000 customers might have positions for 20 operators. ”

“ When a subscriber wishes to be connected to another subscriber, he either turns the handle of a magneto generator, which causes a shutter to fall and expose his number at the exchange, or simply depresses a key which works a relay at the exchange and lights a tiny electric lamp. The operator, seeing the signal, connects her telephone with the subscriber's circuit and asks the number wanted. This given, she rings up the other subscriber, and connects the two circuits by means of an insulated wire cord having a spike at each end to fit the "jack" sockets of the switchboard terminals. ”

“ The provisions for suitable means for preventing the making of a connection with a line that is already switched at some other section of the switchboard, has offered one of the most fertile fields for invention in the whole telephone art. ”

“ The ideal (switchboard) system would be one in which the operator would receive the orders to connect and disconnect from the subscriber orally, by means of a head telephone; to have in front of her a switchboard by which she could connect any two wires of the whole system, however large, without interfering with the other operators. ”

“ When a subscriber on a certain line desires to get connection through the switchboard he turns his generator and throws the drop. The operator in order to communicate with him inserts the plug in which her telephone terminates into the jack, and removes her receiver from its hook. Having learned that it is for a certain subscriber on another line, she withdraws her plug from the jack of the calling line and inserts it into the jack of the called line, then, hanging up her receiver, she turns the generator crank in accordance with the proper code to call that subscriber. ”

“ She is also taught the knack of concentration, so that she may carry the switchboard situation in her head, as a chess-player carries in his head the arrangement of the chess-men. And she is much more welcome at this strange school if she is young and has never worked in other trades, where less speed and vigilance are required.
No matter how many millions of dollars may be spent upon cables and switchboards, the quality of telephone service depends upon the girl at the exchange end of the wire. It is she who meets the public at every point. ”

“ The operator’s telephone is usually equipped with a hand set, (receiver and transmitter) which leaves him with only one free hand for making connections.
4. One switchboard is equipped with but one master, or operators cord, this affords only one means of answering and calling.
Advantages of the Monocord Switchboard.
1. Small, compact, light weight.
2. Simple wiring.
3. Quickly installed.
4. Particularly suited for small central exchanges.
5. Units can be removed quickly, in case of trouble in interior circuits. Any unit can be removed without disturbing other units. ”

“ But the electric-light men also had the advantage of the experience gained by telephone men in building local circuits. It is written that the first electric-light switching devices were derived from the telegraph switch, only enlarged to accommodate the greater volume of current. The strap key, the telegraph key and the switchboard plug were all utilized in central-station electric lighting, and the arc that formed between the terminals following the withdrawal of the plugs was usually blown out with the breath, or whipped out with a cloth, or extinguished with a handful of sand. ”

“ At least seven countries must cooperate to make a telephone message possible.
Perhaps the most extraordinary feature in the Western Electric factories is the multitude of its inspectors. No other sort of manufacturing, not even a Government navy-yard, has so many. Nothing is too small to escape these sleuths of inspection. They test every tiny disc of mica, and throw away nine out of ten. They test every telephone by actual talk, set up every switchboard, and try out every cable. A single transmitter, by the time it is completed, has had to pass three hundred examinations ”

“ Thus, when the cord circuit of a metallic-circuit switchboard is used to connect two grounded circuits together, the tip strand of the cord is the connecting link between the two conductors, while the sleeve strand of the cord merely Page 362 serves to ground one side of the clearing-out drop and one side each of the operator's telephone set and the ringing generator when their respective keys are operated. ”

“ The simplest form of switchboard is that for serving small communities in rural districts. Ordinarily the telephone industry in such a community begins by a group of farmers along a certain road building a line connecting the houses of several of them and installing their own instruments. This line is liable to be extended to some store at the village or settlement, Page 374 thus affording communication between these farmers and the center of their community. ”

“ You could put the entire equipment in a dray. Our switchboard is about as big as an old-fashioned china closet and has three hundred drops. I suppose an up-to-date telephone manager has forgotten what "drops" are and you can't be expected to know. But out our way the telephone companies are coöperative, and as every subscriber owns a share, we all take a deep personal interest in the construction and operation of the plant, discussing the need of a new switchboard and the advantage of cabling the Main Street lead, in technical terms. ”

“ In fact, the more furious the subscriber becomes the less the girl knows about it, for the tiny signal light fails to register except when the hook is moved slowly; or if the switchboard is one where the operator is signalled by a little disk which falls over a blank space the disk fails to move down but remains quivering almost imperceptibly in its usual position. [Pg 119]
After he has placed a call a man should wait at the telephone or near it until the connection is made. ”

“ For a complicated internal service of inter-communications, the telephone is much superior to speaking tubes, as the switchboard system enables the user to communicate with any department without the need of extra tubes. ”

“ Telephonic apparatus consisted of makeshifts and adaptations. It was the period of iron wire, imperfect transmitters, grounded circuits, boy operators, peg switchboards, local batteries, and overhead lines.
2. Development. 1886 to 1896. In this period amateurs became engineers. The proper type of apparatus was discovered, and was improved to a high point of efficiency. In this period came the multiple switchboard, copper wire, girl operators, underground cables, metallic circuit, common battery, and the long-distance lines.
3. Expansion. 1896 to 1906. This was the era of big business. ”

“ Behind this all the wires converging in the office concentrate. The board accommodates 400 different lines. In October, 1878, the parent 'Bell Telephone Company' issued a circular describing a form of brass strip switchboard 'adapted for six circuits.' On February 20, 1879, a circular was issued describing a switchboard which could be supplied at
from 50 cents to $1 per circuit, according to the number of circuits. ”

“ Switchboards, no matter how perfectly made and no matter with how great care they may be installed and maintained, will get out of order. Telephone lines will become grounded or short-circuited or crossed or opened. Such conditions, in a faulty busy-test system, may result in a line that is really idle presenting a busy test, and thus barring the subscriber on that line from receiving calls from other lines just as completely as if his line were broken. ”

“ Soon, therefore, it became obvious that the telephone switch must be compact; all the apparatus must be easily and quickly under control; everything about it must be well made and well put together; the motions required in a connection must be reduced to a minimum, and yet the apparatus must be cheap. The cry of cheapness for a long time obscured the vision of the practical man. In 1881 came the first of the multiple switchboards. This innovation was arranged for grounded and later for metallic circuits, and was designed to eliminate many of the causes tending to slow down the service. ”

“ For the serving of a large traffic from a large number of lines, as is required in practically every city of the world, a very great contribution to the practical art was made by the development of the multiple switchboard. Such a switchboard is merely such a device as has been described for the simpler cases, with the further refinement that within reach of each operator in the central office appears every line which enters that office, and this without regard to what point in the switchboard the lines may terminate for the answering of calls. ”

“ One uncanny device, which would seem to be a mere inventor's fantasy if it had not already saved the telephone companies four million dollars or more, is known as the "phantom circuit." It enables three messages to run at the same time, where only two ran before. A double track of wires is made to carry three talk-trains running abreast, a feat made possible by the whimsical disposition of electricity, and which is utterly inconceivable in railroading. This invention, which is the nearest approach as yet to multiple telephony, was conceived by Jacobs in England and Carty in the United States. ”

“ In outline the operation of a one-way trunk between common-battery, manual, multiple switchboards is, with modifications that will be pointed out afterwards, as follows: When a subscriber's line signal is displayed at one office, the operator in attendance at that position answers and finding that the call is for a subscriber in another office, she presses an order-wire key and thereby connects her telephone set directly with that of a B-operator at the proper other office. ”

“ Each of two persons, wearing dry shoes or rubber-soled slippers, grasps the terminal of one wire in one hand. The other hand is placed flat against the ear of a third person, with a piece of dry linen paper intervening between the hands and the head. If a fourth person, in the room where the induction coil is located, then closes the small switch and speaks into the telephone transmitter, the person against whose ears the hands are being held will hear the speech very distinctly. The ticking of a watch held against the mouthpiece of the transmitter will be heard with startling clearness. ”

“ The wire chiefs must detect trouble under a thousand disguises. Perhaps a small boy has thrown a snake across the wires or driven a nail into a cable. Perhaps some self-reliant citizen has moved his own telephone from one room to another. Perhaps a sudden rainstorm has splashed its fatal moisture upon an unwiped joint. Or perhaps a submarine cable has been sat upon by the Lusitania and flattened to death. But no matter what the trouble, a telephone system cannot be stopped for repairs. ”

“ It may be taken as a fundamental principle in the design of any piece of telephone apparatus that is to be generally used by the public, that the necessary acts which a person must perform in order to use the device must, as far as possible, follow as a natural result from some other act which it is perfectly obvious to the user that he must perform. So in the case of the switch hook, the user of a telephone knows that he must take the receiver from its normal support and hold it to his ear ”

“ All that the earlier automatic system did was to prove more or less successfully that automatic apparatus had a right to exist, and that to demand of the subscriber that he manipulate from his station a distant machine to make the connection without human aid was not fallacious. When it had been recognized that the entire multiple switchboard idea could not be carried into automatic telephony with success, the first dawn of hope in that art may be said to have come. ”

“ Wireless telephony, like wireless telegraphy, but to an even greater extent, is peculiarly suited for the conveyance of marine intelligence. Wireless telephony occupies a unique position in this regard-no operator is required. The additional expense of an operator is an objection to the wireless telegraph in many cases, and forbids its installation. Anybody can operate the wireless telephone. It is also much quicker-words can be spoken more rapidly than they can be put into Morse signals and translated. ”

“ I used on them a switch, that had to be thrown one way by hand, when the telephone was being used, and then thrown back by hand to put the bell in circuit again. But the average man or woman wouldn’t do this more than half the time, and I was obliged to try a series of devices, which culminated in that remarkable achievement of the human brain—the automatic switch—that only demanded of the public that it should hang up the telephone after it got through talking. This the public learned to do quite well after a few years of practice. ”