1,110,367. Automatic exchange systems. INTERNATIONAL BUSINESS MACHINES CORPORATION. 23 March, 1966 [2 April, 1965], No. 12713/66. Heading H4K. A switching network comprises a number of closed meshes defined by conductors arranged in a co-ordinate manner, the intersecting points or nodes being provided with switches for connecting together any pair of conductors. In a 2 co-ordinate network, Fig. 1, subscribers' lines are connected to the nodes N over switches A, and each node may be connected to any one of 4 adjacent nodes over switches X, Y, the object being to interconnect pairs of subscribers over the shortest available path with a low blocking factor in relation to the switching equipment employed. The blocking factor may be further reduced if provision is made for rearranging existing connections. Thus, for example, with the 4 existing connections shown in Fig. 3a, if a connection is required between B33 and B43 it can be obtained by changing the B32, B44 connection to that shown dotted in Fig. 3d. The average path length of a connection may be reduced by allotting a subscriber's line to more than one node. In Fig. 7 (not shown) auxiliary cross-point matrices are employed for connecting any one of 2 (or 4) lines to any one of 2 (or 4) nodes. The arrangement may be extended to more than 2 co-ordinates, and it is found that for a given number of nodes an optimum result is obtained by suitable choice of the number of co-ordinates. The switches at the nodes may be of multi-position mechanical type, cross-bars or reed relays. The switches are conveniently controlled by a central processing unit CPU, Fig. 13, which obtains the addresses of the calling and called subscribers from a line scanner 102 and sends signals indicative of the shortest available path to a switch controller 105. If the CPU fails the memory of the network may be recaptured by the use of a network scanner 106.