Telegraph sounders convert electrical pulses into audible sounds and are used to receive Morse code messages. The message travels as a series of electrical pulses through a wire. Short pulses make a dot, slightly longer pulses make a dash. The sequence of dots and dashes represent letters and numbers. The pulses energize the sounder’s electromagnets which move a lever-arm. The arm makes a loud “click” when it strikes a crossbar and the operator translates the pattern of sounds into the original language. This sounder shows the improvement patented by George L. Foote in 1901 (US Patent 668,257.) Foote placed a hinged bar on the sounding lever so that the armature of the sounder could be adjusted without affecting the adjustment of the whole lever.
The following description was written soon after this sounder was donated. "This is the third style of sounder donated by telegraphic equipment manufacturers for the Mercian Telegrapher's Tournament Association Contest held in Philadelphia on October 30 and 31, 1903. This sounder is a patented construction of G.L. Foote (member of the firm) made by this firm. Pat. No. 668,257 of Feb. 19,1901 is concerned with an improvement in electro-magnets, such as sounders and relays employed in the telegraph service. Specifically this patent covers a means of adjusting the position of the armature (dark strip of metal extending over the tops of the two ends of the electro-magnet) without changing the position or stroke of the vibratory bar or lever. This instrument also employs slotted clamping screws,of modern appearance. Also the yoke or arch supporting the lever pivot is integral with the base or resonator, i.e. it is a one piece construction, probably a casting. The spring adjusting screw is horizontal and projects from the yoke. On top of the lever just forward of the yoke is the patented armature adjustment. The purpose of this invention is to permit closer adjustment of the armature to the magnet coils. This is a 4 Ohm instrument and like the Bunnell instructions the armature must be close to the magnet coils but not touching them. With this adjusting screw working against a spring under the lever it was claimed that a closer adjustment could be easily obtained. This spring can be seen at the yoke end of the lever as it is dark in contrast to the brass lever."
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