Sumter Telephone Mfg. Co. No. 19 "screw top" split shaft

This is a very rare No. 19 Sumter "screw top" split shaft with marked transmitter. The patent on this desk stand includes the design for 3 different versions. Its purpose was to provide the portable telephone with a casing surrounding the central core and enclosing the switching apparatus which could be moved to expose the switches without interfering with the working parts. The preferred design was the split shaft.