London to St. Margaret's Bay 84.5 miles. St. Margaret's Bay to Sangatte (cable). 23.0 " Sangatte to Paris. 199.0 " Paris underground. 4.8 " ----- Total. 311.3 " The resistances are as follows: Paris underground. 70 ohms. French line. 294 " Cable. 143 " English line. 183 " --- Total (R) 693 " The capacities are as follows: Paris underground. 0.43 microfarads. French line. 3.33 " Cable. 5.52 " English line. 1.32 " ---- Total (K). 10.62 " 693 x 10.62 = 7,359 = K R a product which indicates that speech should be very good. 2. _Trials of Apparatus._--The preliminary trials were made during the month of March between the chief telegraph offices of the two capitals, and the following microphone transmitters were compared: Ader. Pencil form. Berliner. Granular form. D'Arsonval. Pencil " DeJongh. " " Gower Bell. " " Post office switch instrument. Granules and lamp filaments. Roulez. Lamp filaments. Turnbull. Pencil form. Western Electric. Granular. The receivers consisted of the latest form of double-pole Bell telephones with some Ader and D'Arsonval receivers for comparison. After repeated trials it was finally decided that the Ader, D'Arsonval, Gower-Bell (with double-pole receivers instead of tubes), Roulez, and Western Electric were the best, and were approximately equal. These instruments were, therefore, selected for the further experiments, which consisted of using local extensions in Paris and London. The wires were in the first instance extended at the Paris end to the Observatory through an exchange at the Avenue des Gobelines. The length of this local line is 7 kms. The wires are guttapercha-covered, placed underground, and not suitable for giving the best results. The results were, however, fairly satisfactory. The wires were extended to the Treasury in London by means of the ordinary underground system. The distance is about two miles, and although the volume of sound and clearness of articulation were perceptibly reduced by these additions to the circuit, conversation was quite practicable.