International Library of Technology · Scranton, International Textbook Co. · leaf 121
Fig. 4. Fig. 5. rule, must be heavier than the kind used for telegraph ortelephone work. Fig. 4 shows an insulator, known as theD. G. (deep groove), that is well adapted for ordinary lines.This insulator is so called to distinguish it from those withsmaller grooves, such as are used for telephone…
Electrical engineering
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