this saving the cost of the covering should be taken into account. This
was 27 cents. Therefore, the investment in the magnesia covering is paid
back in less than four months. The data which we have used were obtained
by the use of a calorimeter measuring the quantity of heat passing
through covering. The other possible method of arriving at this
knowledge would be to accurately measure the condensation of the steam.
In these experiments, owing to several reasons, it was not deemed
advisable to rely upon the second method. Recently, however, I have seen
in the _American Engineer_ of June 12, a report of the proceedings of
the Michigan Engineering Society containing a paper by Professor Cooley,
of Ann Arbor, Mich., in which he says:

"The benefits of covering steam-pipes to prevent radiation are
strikingly illustrated by the following example: The Thomson-Houston
electric-light plant in Ann Arbor has about 60 feet of seven-inch pipe
connecting the boilers with the engines and two large steam-drums above
the boilers: in March, 1887, the steam at the far end of this pipe was
tested to determine the amount of entrained water, the pipes and drums
at the time being uncovered. An average of nine experiments gave 31.01
per cent moisture. In June of the same year, after the pipes were
covered with magnesia sectional-coverings, the quality of the steam was
again tested, the average of five experiments giving 3.61 per cent
moisture; the tests were made by the same men from the same connections,
and in the same manner. The pipes and steam-drums in March were
subjected to a draught, which, of course, aided the condensation. Enough
water passed into the cylinders to retard the engines, producing a
disagreeable noise. In June the weather was warmer and the pipes and
steam-drums were well protected. The quality of steam at the boilers was
tested in June, and showed about three per cent moisture. Assuming that
100 incandescent horse-power were being developed at the time, and that