Elementary telegraphy : a manual for students; written specially to meet the requirements of the ordinary grade of the subject as published in the syllabus of the city and guilds of London Institute (1910)
Pendry, H. W. (Henry Walter) · London ; New York : Whittaker & Co. · leaf 215
re generally Dpattern, which consists of two oblong carbon plates aboutly by i, separated by a sheet of mica having three smallcircular holes to provide air gaps. The line wire isconnected to one plate by a spring, which also keeps thecombiaiation together and places the other carbon plateagainst… … tyj^e lightning protectirs. Two protectors of the C type are shown in Fig. 174,with the iron cover removed. A sheet of mica is j^lacedbetween two carbon plates. The lower plates are fitted intinned brass holders connected to screw terminals, while theother carbon plates are held by spring clips…
Telegraph
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer03inte-591-358.webp)
