Century Telephone tapered shaft, "split shaft"

Rare Century tapered shaft, "split shaft". There is a ring just under the transmitter that unscrews to allow the two pieced shaft to split in half (see picture). Marked transmitter and back cup. Century's signature "tear drop" design in the switch hook cut out. Please see the original ad from a 1902 issue of Electrical Review magazine showing how the split shaft works. Also a scan from an original Century Telephone advertisement in the 1904 issue of The American Telephone Journal showing this split shaft telephone.