Crosley patent telephone

No. 1115, wall model, walnut case, microphone with wood diaphragm and 4 carbon pencils, side contact in the manner of a Morse key, turned Bell-type receiver, 7 brass connectors. Note: Crosley improved on David Hughes' invention of the simple carbon pencil microphone by using four carbon pencils to improve the sensitivity of the transmitter and the range of the sound transmission. Instead of only a few 100 yards, transmission of up to 8 miles was now possible. Crosley's microphone was used with the telephones manufactured by Blakey and Emmott, which were purchased in large numbers by the British postal service and were also used in other countries.