der,
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.

Further trials were also made from the Avenue des Gobelines on
underground wires of five kilometers long, and also with some renters
in Paris with fairly satisfactory results. The selected telephones
were equally efficient in all cases, which proves that to maintain
easy conversation when the trunk wires are extended to local points it
is only necessary that the local lines shall be of a standard not
lower than that of the trunk line. The experiments also confirm the
conclusion that long-distance speaking is solely a question of the
circuit and its environments, and not one of apparatus. The
instruments finally selected for actual work were Gower-Bell for
London and Roulez for Paris.

3. The results are certainly most satisfactory. There is no circuit in
or out of London on which speech is more perfect than it is between
London and Paris. In fact, it is better than I anticipated, and better
than calculation led me to expect. Speech has been possible not only
to Paris but through Paris to Bruxelles, and even, with difficulty,
through Paris to Marseilles, a distance of over 900 miles. The wires
between Paris and Marseilles are massive copper wires specially
erected for telephone business between those important places.

4. _Business Done._--The charge for a conversation between London and
Paris is 8 s. for three minutes' complete use of the wire. The demand
for the wire is very considerable. The average number of talks per
day, exclusive of Sunday, is 86. The maximum has been 108. We have had
as many as 19 per hour--the average is 15