First printing of Bell's paper on telephony.
A watershed in telecommunications.
This paper encapsulates a pioneering moment in telecommunications, initiated by Bell's innovative work in 1874 on a tuned system of telegraphy and the study of sound waves in the human ear. Merging these investigations, Bell formulated the telephone's theory, overcoming significant challenges through the concept of an 'undulating' current.
"In 1874, while experimenting with a tuned system of telegraphy, and also studying the path of sound waves in the human ear, he combined two investigations and worked out the theory of the telephone... Bell surmounted this obstacle by use of what he termed an 'undulating' current. Even so he succeeded only after a long and discouraging experiment and he produced three telephones before he felt equal to a public demonstration in 1876." - PMM