The half horse power engine consumed 1148 cubic feet of
cold air, and of heated air 791 cubic feet per horse power and per
hour. It should be mentioned that these, the most valuable and
suggestive of all the trials carried out by Professor Riedler, were
conducted with the greatest care, two distinct modes of measuring the
air supplied being followed on two occasions for each test; it may
therefore be considered that the results given are absolutely correct.
The trials were made with an old single cylinder Farcot engine,
nominally of 80 horse power, but indicating over 72.3. With this
engine the consumption of air varied from 465 to 517 cubic feet, the
larger consumption being due to the lower temperature (129 deg. Cent.)
to which the air was raised before admission; in the most economical
result the temperature was 160 deg. Cent. The volumes of air referred
to are, of course, in all cases taken at atmospheric pressure.
Among the important losses that have to be reckoned with in every
system of distributing motive power from a central station--whether by
steam or by electricity, water, or compressed air--losses must occur
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.
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