The Locomotive - Lighthouse Survival Blog

68 THE LOCOMOTIVE. [Mat,
ning, and it continued to run until 3:04. During all this time there had been no sign
of leakage from the girth-joint, except the slightest trace of vapor, which had been
occasionally visible between 12:30 and 2:20, when the air in the boiler-room was still.
At 3:04 the quarry pump was stopped, and after waiting just one minute for the circu-
lation to subside a little, the inspirator was started (see D). The boiler promptly rose
until it was at least .28" above the normal position. (The pencil, unfortunately, ceased
to mark for a short time, and the dotted part of the record is conjectural.; The girthjoint
plainly showed distress, and at 3: 13 (see E) it was leaking water quite freely. At
3:19 (see F) the inspirator was shut off, but still the leak continued, and the boiler
maintained its abnormal position. At about 3:27 (see 67) the quarry pump was started
again, and the resulting circulation speedily equalized the temperature in the boiler so
that at 3: 33 (see H) the boiler was resting on the middle saddle, and the leakage had
entirely disappeared. The quarry pump continued running, and at 3:43, when the test
was discontinued, the boiler was still in its normal position.
It was thought that the diagram we have described would suffice to demonstrate
that the chilling action of the feed-water was
responsible for the trouble that the owners of
this boiler experienced, but as it was found im-
practicable to regulate the flow of water from
the bucket satisfactorily, the apparatus was
modified to some extent, and the experiments
were repeated. The modification consisted in
the substitution of a clock for the water bucket,
as shown in Fig. 4. The face and hands of
the clock were removed, and a carefully-turned
hardwood pulley, 1%" in diameter, was se-
cured to the hour spindle. The cord from the movable board was passed completely
around this pulley, and to the end of the cord a weight was attached, which was found
by experiment to be almost sufficient to overcome the friction of the board.
With the modified apparatus a new test was made, substantially as before. Marks
were made on the moving board, at known intervals of time, for the purpose of testing
the regularity of its motion, and it was found that in the improved form of the apparatus
the motion of the board could be considered, without sensible error, to be absolutely uni-
form. The lest was begun at 10: 22^ a. m., at which time the quarry pump was running.
At 10:23 the inspirator was started, with the pump still running, and for nine minutes
there was no noticeable effect. The water level was purposely carried very high, and at
10:32 the boiler began to rise from the saddle, the circulation apparently being in-
sufficient to take care of the large body of feed that was introduced. The inspirator
was stopped at 10 :
34,
Fig. 4.
Re< ordixg Apparatus.
but the boiler continued to rise until about 10 : 36. The girth seam
began to leak water about 10:32. and at 10:38, four minutes after the inspirator was
stopped, the circulation seemed to succeed in equalizing the temperature again, for the
boiler went down promptly until it rested on the saddle, and the leak disappeared.
From this time until 10 : 57 the boiler did not leave the saddle by more than the hun-
dredth part of an inch. At 10:57 the quarry pump, which had been running ever since
the experiment began, was stopped, and the boiler began to rise very slowly, and it was
a trifle more than .04" above the saddle at 11:28. It is not easy to say what was the
cause of this slight variation, but as the boiler was uncovered, and the cool, out-door air
blew against the bottom of it through a window, it is possible that the chill so produced
was sufficient to cause the observed rise. At 11 : 28 the inspirator was started, and the
—
Improved Form of the