The Birmingham age-herald., 1907-08-25
MYSTERIES OF THE TERMINAL ROOM" Remarkable Apparatus of the Telephone Exchange FEW PEOPLE UNDERSTAND Thousands of Miles of Wire With Hundreds of Thousands of Con-
 nections All in Single
 Room.
FEW PEOPLE UNDERSTAND

Boston Aug. 24-(speciaD.-There is mysterious whispering gallery maybe just around the corner from your office or in a quite side street not far from your home. where. every hour of the liyelong day. flows the current of talk from hundreds of lips, but there is nev- or sound to break the stiffness. A score of times in the last week, probably your own voice has fitted through this silent chamber, yet the chances are that you have never even suspected it's ex- istence 10 say nothing of having step ped within it's doors. For this is the important but almost unknown region of the telephone exchange called the ter minal room"
 Most people picture central as an of fee in which d number of young women sit before a switchboard deftly joining into continuous threads the myriad strands Of copper that are the web and wool of the telephone system. That is only part of the exchange. though-a very necessary part. to be sure. but one that by itself would be of little service. The apparatus auxiliary to the switch
 
 lures of the telephone system. and this is located in the terminal room.
 The terminal room gets it's name from the fact that in it terminate all the cir cults of the exchange. If it were possi- ble to run the wires from the subscrib- CTS telephones and the trunk" circuits between central offices directly into the the switchboard it would simplify mat ters enormously As matter of fact, though il is not impossible to do any such thing. There are two distinct re- quirements in operating an exchange; the first has to do with answering the calls of telephone users and taking their orders, while the second is concerned in calling other telephone users connected 1 with the same office or with distant of fees and establishing communication be- tween any two stations as the engi- 1 neers call subscribers telephones Ob- | Viously. an operator can take orders ] from only a limited number of lines, whether the number is 10. 30, or 100 de- | bends upon how much each line is used. ! By constant observation the load" on | each operator is carefully adjusted in all | Bell exchanges 10 make sure that no 1 young woman has more to look after | than she can do properly and maintain 1 the Bell standards of service But every | operator must have within her reach | means Of connecting any or the lines on l which she answers with any of the | thousands of lines that give communca- ton with other subscribers in the same exchange or are used for "trunlIng' calls to other exchanges
 While there is but one circuit from the central office to each subscriber l there must be. then, two distinct sets of terminal points in the switchboard for 1 each subscribers line. With the extra 1 ordinary growth of the telephone system l and the steady increase in it's use the eX change must have such heXibilty, so 10 call it. that the innumerable changes go- ing on all the time-changes caused by | the removal of q subscriber from One part of the city to another, by his giving up one class of serviee to take better class by suddn increases in the traffic on certain individual llnes and so on can be made quickly, conveniently. and economically The terminal room takes care of all of these complications. In it the outside circuits and the two different sets of switchboard circuits-those used for answering and those for caling-are brought together in such an ingenious way that the connections may be shifted | almost in an instant, while every circuit in the office is made accessible for test Ing in case of trouble" and for repair. 
 
 system newly constructed or ramodeled | during the past few years the outside i lines are brought into the exchange 1 building in cables. Even in small places, i where the wires to subscribers offices | and houses are strung on poles, the cir ! cults are brought together at "termi- nal pole" outside the exchange and put | into cable form Where the wires are underground the conduit system centres | at the central office building. coming | from all directions to a tunnel beneath | the street where the cables are suspend | ed one above another along the side l walls and led into the basement from | which they are carried to the terminal l room through chute or ehaft In the terminal room the cables are broken apart and ''distributed."
 If you visit this part of a city eX change the first thing to catch your eye will he two long. narrow racks of iron, reaching almost from the floor to the | ceiling their ladder-lke shelves crossed | and recrossed with parti-eolored cords. One of these racks Is known as the | main distributing frame" and Is the | means of connecting the outside circuits l with the propper terminal points in the | multiple" of the switchboard through | which the operators call whenever you | may ask for. The other Is the inter- | mediate frame where connection Is | V terminals in the board At the outer | side of the main frame are the heat | ooils"-llttle cylinders of metal held In | place by brass springs which would ex- pand and drop out. thus breaking the | circuit if an overload of electricity got l into the outside wires from some high | tension line, power. light, traction, or | whatnot The heat coils thus protect the | sensitive and costly apparatus of the ex l change against injury by foreign cur | rents.
 At the outside of the main frame ale | the functions of the switchboard circuits. | Between the two sides are flexible jun | per wires by means of which any inside | circuit may be connected into one sim ply by soldering the opposite ends of the same jumper to both. There are thou l sands of these tiny soldered connections | fin the main frame and thousands of oth- | CTS in the intermediate frame, which is | similar in construction. Ss methodically | is the whole arranged and marked with | the regular line numbers that at any | point in the terminal room given cir | cult may be picked out instantly and | the seeming maze of wires traversed | without danger of straying.
 Beyond the frames is a third rack on | which are set the ingenious relays" that operate the electric lamp signals | in the switchboard. These are enclosed l in numbered japanned boxes arranged | tier upon tier each subscribers line haV- | ;,c ouup relav-a delicatelV adiuSled |