In 1710 there were five churches in the Carolinas; in1722-1723they formed the presbytery of James Island, which (after 1727) went through the same struggle as the synod of Philadelphia in reference to subscription; and in 1731 the parties separated into subscribers and non-subscribers.
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.