[GreenKeys] Teletype (telephone) Local Loops

[Jim Haynes]

On Mon, 25 May 2020, Roy Morgan wrote:
> “The Green Book”
> Tu Wit:
> Principles of Electricity
>   applied to
> Telephone and Telegraph Work
>
> November 1938
> (Reprinted with corrections, January, 1941)
>
And there are other editions.  1930, 1953, 1961