d of an engine of her
class (30 tons). We started up the 100 foot grade, and found we could
barely crawl, and our engineer got furious over it. He thought they
were repeating a trick already attempted by screwing down a brake in
ascending a grade. We detected it, however, and found a pair of wheels
nearly red hot. Upon this occasion we found nothing amiss, except full
cars where they had reported only a light load. We pulled to the top
of the hill, the steam blowing off furiously all the time.

This was a new experience to the Italians, and might surprise some
Americans. When we arrived at the station, the inspector-general and
his corps of engineers were evidently amazed, and it was evident we
had captured them. He said to me, "I can congratulate you, signor, on
possession of a superb machine."

Afterward one of the engineers said to me: "Do not let it be known
that I told you what you have hauled or I shall lose my place, but you
have drawn 50 per cent more than the maximum load of one of our 40 ton
engines." I said: "You attempted to 'stall' us, and when you try it
again, be fair enough to give me a flat of pig iron, and as you pack
cars on one end I will pack pig iron upon the engine until she will
stick to the track, but rest assured that you will not be able to get
that steam down." The experience with that engine proves conclusively
to my mind that the general principles of steam making are the same
for both stationary and locomotive practice. The grand secret of the
success of that Wootten engine was the enormous area of the grate
surface, being, if I remember correctly, 7 by 9 feet, permitting thin
fires to be carried and complete combustion to be obtained before the
gases reached the boiler tubes. An enormous crown sheet was presented,
and that is where the bulk of the work of any boiler is done.

Thin fires accomplish this. As already stated, a given amount of coal
generates a given amount of gas, and this gas requires a given amount
of air or oxygen. This air must be supplied through the grate bars and
then pass through the interstices of the mass of heated coal. It
requires about 10 cubic feet of air to consume one cubic foot of gas.
In stationary boilers we find that if we use "pea" and "dust" coal, an
extremely thin layer must be used, or the 10 feet of air per foot of
gas cannot pass through it; if "chestnut" coal be used, the thickness
may be increased somewhat; "stove size" allows a thickness of six