in the mains by which the power generated is transferred from the
point of production to that of consumption. In the case we are now
considering very careful tests were conducted in 1889 by Professor
Kennedy, to whose report we have already referred. Since that time
important changes have been made by the Compressed Air Company, at
Paris, in the details of distribution, and on this account the later
investigations of Professor Riedler on the losses due to this cause
are of special interest.

Before its admission into the mains a certain loss occurs at the St.
Fargeau station, in the large reservoirs to which the air is delivered
from the compressors. This question of preliminary storage was one
that received considerable attention when the designs of the new
station on the Quai de la Gare were being considered. It was intended
to construct very large receivers in the basement of the station, and
the foundations for these were even commenced. It was decided,
however, that for the 10,000 horse power which is to form the first
section of the new station, and for which the complete system of mains
has already been laid down, storage reservoirs would be unnecessary,
and a saving both in first cost and subsequent loss of air would be
effected. The length of mains of 19.69 in. diameter is so considerable
that they will contain at all times a sufficient reserve of air to
prevent any irregularities in pressure at the motors.

With reference to these mains it may be mentioned that, unlike the
11.81 in. conductors of the St. Fargeau system, of which 17 kilometers
are laid in the Paris subways, the new mains are entirely laid in the
streets, it having been found impossible to make room for these large
pipes in the subways already crowded with telegraph and telephone
wires, water mains, etc.