In a large city, where several inter - connected exchanges have to be built and thousands of subscribers are put into communication with each other, the service is at once more costly and more valuable than in a small town with a few hundred subscribers accommodated in one exchange.
An exchange is a central station to which wires are brought from the various subscribers in its neighbourhood, any two of whom can be put in telephonic communication with each other when the proper pairs of wires are joined together in the exchange.
When the subscribers in a local area exceed a certain number, or when for some other reason it is not convenient or economical to connect all the subscribers in the area to one exchange, it is usual to divide the area into a number of districts in each of which an exchange is placed, and to connect these district exchanges together by means of " junction circuits."
These inter-area or long-distance lines, called trunk circuits in England, terminate at one exchange in each local area, and between that exchange and the various district exchanges junction circuits are provided for the purpose of connecting subscribers to the trunk lines.
This board was equipped with spring-jacks and annunciators (calling-drops) for the subscribers' lines, and with flexible cords terminating in plugs for connecting purposes.
Several single switchboards like that described may be employed, each devoted to a certain section of the subscribers, and placed in care of an operator.
In these circumstances, when, as frequently will be the case, the person calling desires to be put in communication with a subscriber who belongs to another section, connexions must be established in the office between the two sections; this necessitates additional switchboard arrangements, and also increases the time required to put subscribers in communication with one another.
All the subscribers' lines are connected in order to jacks on the first two or three or four operators' positions, and these connexions are repeated or " multipled " upon each succeeding similar group of positions.
Hence this operator, when signalled in the ordinary way, can put any one of these subscribers in connexion with any subscriber whatever, without the necessity of calling upon another operator to make connexions.
This advance did not merely remove the primary batteries from the subscribers' stations; it removed also the magneto-generator, and at the same time it modified considerably the conditions governing the exchange operating.
With the adoption of relays the signalling between the subscribers and the exchange became automatic, and, with the introduction of the principle of double and automatic supervision on the cord circuits, it became possible for the operators to tell at any instant the state of a connexion.
8) a repeating coil is placed in the cord circuit, and when two subscribers are connected together the winding connected to the line of the subscriber who is talking for the time being acts as primary, and the other, which is in the line of the listening subscriber, as secondary.
When one of two subscribers connected together by this arrangement talks, the Exchange From the Post Office Electrical Engineers' Journal.
When both lamps glow, the operator, who thereby knows that both subscribers have restored their instruments, discontinues the connexion.
Of the calls originated at an exchange are for subscribers connected to other exchanges, and in these cases the junction plant forms a considerable fraction of the whole equipment.
At the outgoing end the circuits are multipled on the subscribers' switchboard, while at the incoming end they terminate in plugs on a special incoming junction switchboard upon which the subscribers' lines are multipled in the usual way.
Each of the subscribers controls a signal at A, and when either or both of the telephones are replaced, the action is indicated by the lamps there.
If there be a line free, or when the turn of the call is reached, particulars of the connexion wanted are passed to the distant end, and the trunk operators request the local exchanges to connect the subscribers by means of junction I F..?
The call is controlled by the trunk operators, the junction circuits being equipped in such a manner that the subscribers' signals appear at the trunk exchanges, from which point disconnecting signals are sent automatically to the local exchanges, when the connexions between the trunk and the junction circuits are removed.
In suburban and rural districts subscribers are usually served by means of bare wires erected upon wooden or iron poles.
As subscribers' lines are invariably short, the smallest gauge of wire possessing the mechanical strength necessary to withstand the stresses to which it may be subjected can be employed, and bronze wire weighing 40 lb per mile is commonly used.
The conductors used for subscribers' circuits are of copper weighing from 10 to 20 lb per mile.
Various methods of making the connexions between the large main cables and the subscribers are in use.
The company consented to free intercommunication between its subscribers and those of the Post Office, and undertook to charge rates identical with those charged by the Post Office.
In 1885 there were only 3800 telephone subscribers in London and less than io,000 in the rest of the United Kingdom, and telephonic services were available in only about 75 towns, while in the same year the American Bell Telephone Company had over 134,000 subscribers.
Subscribers outside the county of London pay only £4 in annual subscription and id.
Per call to subscribers on other exchanges.
For subscribers within half a mile of the exchange, £1, 5s.
For subscribers who desire the telephone for occasional use, the party-line system has been devised, whereby several telephones are connected to one line leading to the exchange.
Per call to subscribers within the county and 2d.
Subscribers to exchanges may also make arrangements to have all telegrams (except Press telegrams) ad - dressed to them delivered by telephone instead of messenger.
It brought in the enormous sum of £1,000,312,950 from no fewer than 5,289,000 subscribers; and Mr. Law justly hailed it both as an expression of the will of the people to win the war and also as evidence of the financial ability of the country to see it to a successful conclusion.
In 1529 the la,ndgrave signed the "protest" which was presented to the diet at Spires, being thus one of the original "Protestants;" in 1530 he was among the subscribers to the confession of Augsburg; and the formation of the league of Schmalkalden in the same year was largely due to his energy.
He proposed to bring out an edition of Shakespeare by subscription, and many subscribers sent in their names and laid down their money; but he soon found the task so little to his taste that he turned to more attractive employments.
The subscribers engaged by oath to maintain religion in the state in which it existed in 1580, and to reject all innovations introduced since that time, while professed expressions of loyalty to the king were added.
His wealth and power were enlarged by gift of the parliament which met on the 14th and rose on the 19th of April - a date made notable by the subsequent supper at Ainslie's tavern, where Bothwell obtained the signatures of its leading members to a document affirming his innocence, and pledging the subscribers to maintain it against all challengers, to stand by him in all his quarrels and finally to promote by all means in their power the marriage by which they recommended the queen to reward his services and benefit the country.
The second year ended with 7000 subscribers and a further loss of $2000.
Its subscribers were found throughout all quarters of the northern half of the Union from Maine to Oregon, large packages going to remote districts beyond the Mississippi or Missouri, whose only connexion with the outside world was through a weekly or semi-weekly mail.
The second was just issued, and the subscribers, in their anger, refused by thousands to receive it.
It is worth noticing that Mill was one of the subscribers, and that Littre continued his assistance after he had been driven from Comte's society by his high pontifical airs.
The subscribers' lines in an exchange are arranged in groups of moo, which are divided in turn into sub-groups of 100 each.
Telephone subscribers may also obtain the services of an express messenger by telephoning to the nearest post office connected with the exchange.