Morning journal and courier. [volume] (New Haven [Conn.]) 1848-1894, 1881-03-02
shefaeld Scientific school.

Professor FroSvbrIdge,s Coil Boiler-A
Full and Complies Description OF the
Inventfon-Lectureb by Professor Honey.
Mr. f. r. Honey, of the Yale Art School,
lectured in the Shefield Scientific School
course to mechanics last evening before
large audience, giving complete description
of Professor Trowbridge's coil boiler, which
is exciting much interest both in this country
and in Europe. A full account of this i'm
portant invention, as given by the lecturer,
follows.
AS the time in which am allowed to speak
is limited, shall be compelled to confne
your attention mainly to description of
Prof Trowbridge's boiler in its present state
of development, in order that you may gain
clear idea of the machine. With the aid of
the drawings before you and some projec-
tons on the screen, I shall try to explain to
you the construction of the boiler and feed
pump and show how they work. Before Civ
ing this description, however, will offer you
few remarks on the origin of this invention
and on the demand which it is intended to
supply. The inventors who have taken out
the patents are Prof. w. P. Trowbridge, who,
as you know, was professor of mechanical
engineering in this institution and is now
professor of engineering in the Columbia
School of Mines, and Mr.. Thomas w. Mather,
graduate of the Sheffield Scientific School
The Importance of devising q. small motor
was impressed upon Prof Trowbridges mind
while he was vice president of the Novelty
Iron Works, ten or eleven years ago, and he
was then led to plan what has since been
contaminated at the cost of many expert
ments and after many delays. Prof. Trow-
bridge had studied the many varieties of en-
gines designed for small motors and learned
their defects and concluded finally that a
small motor to be of universal use and appi-
cation must be a steam motor, and that the
possibility of making steam engine ayaila-
BILE for very small power depend
ed entirely upon the construction of the
boiler. No very light boiler had hereto
| fore been made which possessed at the
same time high cooperative power, which
could bear any pressure that could possibly
| be brought upon it, up to several thousand
pounds per square inch, which would keep
/ its pressure of one hundred or two hundred
pounds per square inch steadily while eyap-
| Grating water rapidly, which was automatic
| in the feeding of the water and also of the
| fuel, and which was both light and cheap in
| construction and absolutely non explosive.
| All these qualities Prof. Trowbridge's boiler
possesses In small boilers, as heretofore
made, the necessity of frequently opening the
doors and adding new fuel causes the fire to
slacken and the steam pressure to fuctuate;
and no arrangement had been made which
| would in very small bulk give heating sur
face enough to evaporate water with suf-
ficient rapidity. The evaporation of nearly
nine pounds of water with one pound of
coal or combustible, while at the same time
the rate of combustion is kept as high as
twenty-five pounds of coal to each square
foot of CRATE surface per hour, is perform
ance not exceeded by the best large boilers.
Prof Trowbridge's boiler gives in an ordi-
nary trial test 81 pounds of water evaporated
for one pound of combustible, and burns 463
pounds of coal on each square foot of CRATE
per hour, or at that rate, as the crate surface
is only twelve inches in diameter.
The weight of an ordinary 5-horse power
boiler is 1875 Tbs. AS, without a pump, esti-
mated water contained in the same, 700 lbs.
Total weight 2,O75 lbs. The weight of d s.
horse power automatic boiler, with pump, is
700 lbs. Estimated water contained in the
same, 40 lbs. Total weight 40 Tbs. We
see by this estimate that Trowbridge auto
matte boiler and pump with water, that is
with steam up, weighs little over one-third
of the weight of an ordinary boiler and water
without pump.
Let us now compare the weights of another
size. An ordinary 12-horse power boiler
without pump weighs 9, $50 fbs Estimated
water contained 1900 lbs. Total weight
4, $50 TBS. A 12-horse power automatic
boiler with pump weighs 1 200 lbs. Esti-
mated water contained, about 100 TBS. Total
weight 300 fbs That is little less than
one-third the weight of an ordinary boiler
under similar conditions. These figures
speak for themselves and show how great an
advantage is possessed by the Trowbridge
boiler in the matter of weight as compared
with other kinds in use.
The applications of boiler of this type are
very numerous. As examples we may name
the following purposes for which light and
safe boiler is of especial value, viz, for farm
work in it's many branches for dwelling
houses; for printing presses; for light ma.
chinery and woodworking tools; for hoist
ing and pumping /; for fire engines for
street cleaning purposes; for propelling
small boats, street cars, prof. Trow bridge has
designed an air condenser in which very
large surface area is exposed to the action of
the air when the car is in motion. The steam
exhausting into this vessel will be rapidly
condensed, and the noise, which has hereto
fore been incidental to the exhaust of high
pressure engine, will be ayoided), and for
driving sewing machines, etc. For mining
purposes the Trowbridge boiler may be car
ried from one part of mine to another with
ease and employed for driving drills, in
word, it may be set up rapidly at any time
Whereon work is required to be done. The
demand for boiler of this kind comes large
ly from men who cannot afford the expense
of an engineer, who know nothing of steam,
but who want an engine and boiler which
they can manage themselves, one that will
run steadily without great cost or liability to
damage. The requirements for such boiler
may be summed up under the following
heads viz, LIST. It should be perfectly SAFE
Under all circumstances, with any kind of
usage, there should be no possibility of dan
ger to life from explosion. I'd. It should be
SO constructed that only very small amount
of time need be spent in running it. Sd. It
should be portable and as light as possible.
With regard to the first requirement., viz,
safety, I have only to call your attention to
the fact that the coil which is before you
forms the boiler to convince you that this
boiler is practically non-explosive. Gre
marks.) 4 inch pipe ] of an inch thick
will stand a pressure of four thousand
pounds to the square inch. I do not know
what is the highest pressure to which it has
been subjected. I can, however, state that
it has been pressed higher than the gauge
Will register, w., zOO IDS per square 1nch
Mr.. Mather has applied great variety of
tests to the strength of this boiler. Some of
these tests have been accidental. Before he
had perfected the feeding apparatus, the
pump occasionally failed to do duty, and no
water being pumped into the boiler very
few minutes elapsed before all the water that
was in the coil was evaporated. The conse-
quence was that the pipe became red hot.
this, Mr.. Mather did not
hesitate to pump in a fresh supply of water
which Immediately flashed into steam of high
pressure, but no harm was done. This was
one of the occasions when the
gauge was incapable of registering |
the full pressure. Mr. Mather report |
ed that the engine made very large number |
of revolutions per minute, and that the little |
twenty five foot boat, which it was driving, |
travelled through the water for few minutes |
at very high speed. I need hardly state |
that had the boat been fitted with an ordin- |
airy boiler, under similar circumstances, Mr.. |
Mather would have travelled more rapidly |
and in different direction, nor would any |
report on the experiment have been forth
coming. ..,sy
This coil has been red hot eight or nine |
times On each of these occasions since |