The accompanying phonoplex coil appears to be satisfactory in every respect except provision for insulation, which is an important one, as the momentary c. m. f. obtained from the coil is about 200 volts. I would suggest that the wires leading beneath the base to the terminals be in all cases insulated by thin rubber tubing with the bottom of the terminals covered by a thin layer of shellac or paraffine wax; also that a thing layer of shellac be spread in the form of varnish over the outer layer before coating with braid to prevent the possible absorption of moisture. A. E. Kennelly

Kennelly, Arthur Edwin

Tate, Alfred Ord

1889-12-11

1880-1889

Letter

Cellulose, resins, and related products

Phonoplex and railroad telegraphy

LB035205

LB035

[LB035205], Letter from Arthur Edwin Kennelly to Alfred Ord Tate, December 11th, 1889

140:78

Thomas Edison National Historical Park

Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University