The varioplex — A new development in telegraphy

The varioplex method of telegraphic operation provides each pair of stations connected together by it an ever-ready two-way channel for the exchange of traffic, which occupies a band width of zero when idle and of a variable width when busy, depending upon extent of simultaneous usage by other connected stations. It possesses certain advantages over, or in supplement to, other forms of manual and machine switching or repeatering. Adapted to the use of private subscribers through telemeter service, it is finding extensive application in the telegraph plant. A good deal of current effort in the telegraph engineering field is being directed toward the solution of problems of trunking and switching. Basically, these problems arise from the circumstance that important trunking centers, like Boston, Atlanta, or Los Angeles, have tributary to them most of the less important telegraph offices in their respective surrounding areas. That this is so with respect to the many branch telegraph offices and tie-line connections which dot the larger American cities requires no explanation; the growth of commerce along the railroads has made it no less true of cities and towns many miles from trunking centers. The existence of fanned-out local telegraph circuits around Boston as a hub, to take that city as an example, is inherent in the commercial relationship of most New England towns to its dominating city. It can be appreciated, then, why the Boston office, in years past, has acted not only as the terminal for a considerable day-to-day traffic between Taunton and Boston but also as the relay point for the less frequent messages between Taunton and New York. This situation exists the country over. Of recent years, improvements in the transmission qualities of these tributary circuits have made it possible to terminate them, almost universally, in printing telegraph equipment.