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 97
P.O. form if t in^ont s^lvaiiometpi. … Fifi. 67.—Illustrating tlie construction of a tangent scale. a deflection of 60 represents a current value three timesgreater than that producing 30°. Instead, however, ofascertaining the values of deflection by reference to a TELEGRAPH INSTRU.UENTS 87 tangent table, a scale is formed on the…
Telegraph
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