5
ARTICLE III.
ON SAVING FUEL, AND INCREASING POWER, BY
THE NEW AND SIMPLE PRINCIPLE.
A QUESTION naturally arises; what proportionate
increase of fuel is required to increase the power? It has been generally
supposed, that double fuel was requisite to produce double elastic power,
and keep it up to work an engine; and consequently nothing was to be gained
on that principle. Yet, had we closely observed the works of nature, how
rapidly the power must increase to produce the effects we have often seen,
we would readily have drawn another conclusion.*
*If a bottle of water tightly corked be set near the fire, the cork will presently fly out, or the bottle will burst with a loud report. Put half a gill of water into a musket barrel, ram a tight wad strongly down, put the barrel into a fire, and it will shoot with a force and report equal to powder. A coppersmith made a strong globular but small vessel for one of his customers,who next day came with the appearance of one just escaped from the grasp of death, to relate that he had filled the vessel with water, set it on the fire, and that after some time it exploded with the noise of a cannon; that he had narrowly escaped with life, and was determined never to try another experiment on the power of steam. Other accidents more tragical might be mentioned. But shall we refuse to use as much power as we want because we can increase it to a dangerous degree?
Observing the principles of nature, in the production of such accidental
effects as before stated, I, in the year 1784, conceived the principles
and arranged the means of working steam engines with a power equal to 10
atmospheres, and applied, in 1786, to the legislature of Pennsylvania for
the exclusive right of propelling
6
Experience now teaches, that if 4 pecks of fuel per hour,
will heat a quantity of water to produce steam of elastic power equal to
15 pounds to the inch, or equal to
land carriages by steam in that state, for twenty-one years; but they conceived me to be deranged, because I spoke of what they thought impossible, and refused. I applied next to the legislature of Maryland, who granted me the exclusive right for fourteen years, because, said they, it can injure no man and may cause him to produce something useful. This term I conceived to be too short; the grant however, had the effect to prevent me from relinquishing my studies on steam: time will shew the better policy of the legislature of Maryland in this case.
I cannot suppose that any person, who understands the principles of mechanics,
after having seen a rocket rise into the air by the reaction of its fuse,
under all the disadvantages with which the power there acts, and after having
known that the power of steam is equal to that of the fuse, could any longer
doubt of the sufficiency of the power of steam to do any thing, even to
carry the whole engine up into the air. If so, why will it not do to propel
carriages and boats? For twenty-one years last past I have been endeavouring
to convince my countrymen, that principles do exist by which steam engines
can be made useful in all cases where a powerful agent is wanted. I sent,
early in 1795, drawings and specifications to England and had them shown
to engineers there, all without effect. I am sorry to relate, that seventeen
years passed before I could conceive it to be my interest to expend one
thousand dollars, to try experiments to put my principles in practice. In
1801, I commenced, and at the expense of two thousand dollars, besides my
own labour and time, valued at one thousand dollars more, I at last produced
an engine realizing in practice the whole of my theory. Having now made
perhaps the greatest improvement, and most useful invention on steam engines
ever produced by any one man, I expect to be attacked from all quarters:
in every state in the union will, no doubt, be found one or more inventors
who have made the same invention, as was the case with my improvements on
merchant flour-mills, after they
7
one atmosphere, 5 pecks consumed per hour, will produce
steam equal to 30 pounds the inch, or two atmospheres, and keep the power
up to work an engine; * holding true in practice, that every addition of
a small quantity of fuel to be consumed in an equal time, doubles the elastic
power of the steam, and keeps it up to work an engine; double fuel producing
about 16 times the bulk, consequently 16 times the power and effect. This
will not appear doubtful, after we are informed, that philosophers have
made a set of accurate experiments, to ascertain the elastic power of steam
produced by different degrees of heat, from which they deduced the following
formula or rule, viz. That every addition of about 30 degrees of heat, by
Fahrenheit's thermometer, to the water, be the temperature what it may,
doubles the bulk and elastic power of the steam.
were published. In that case I was attacked from a quarter from which I could not possibly expect it; but the justice of my country continues to give me the honour (I wish I could say, and the profit) of my invention.
*1089 pounds of dry oak are equal to 600 pounds of Newcastle coals, in producing equal quantities of heat. Repertory of Arts, series ii. vol.1.
See the experiments in the American edition of the Encyclopedia, vol.17,
from which the following scale is constructed.
8
SCALE OF THE ELASTIC POWER OF STEAM, PRODUCED
BY DIFFERENT DEGREES OF HEAT IN THE WATER.
| Degrees of heat in the wateradding 30 degrees every step | Elastic power to the inchare of piston, or safety valve. | Atmopsheres |
212 gives 30 |
15 pounds, equal to | 1 |
242 30 |
30 | 2 |
272 30 |
60 | 4 |
302 30 |
120 | 8 |
332 30 |
240 | 16 |
362 30 |
480 | 32 |
392 30 |
960 | 64 |
| 422 | 1920 | 128 |
By this scale it appears that doubling the heat from 212
to 424 degrees in the water, produces 128 times the elastic power of steam;
and that as the heat is increased
9
in an arithmetical progression, by the addition of 80 degrees, the elastic power of the steam is increased in a geometrical ratio, multiplying by 2. But this may be only true at or near the heat of 212 degrees; the geometrical multiple being greater than 2 below 212 degrees, and less than 2 above 212 degrees of heat; falling short 15/1000 parts, at every step of 11 1/4 degrees increase of heat, as has been the result of another set of experiments, made by Dalton.* So that doubling the heat in the water, may not produce more than 75 or 100 times the elastic power of steam.
Let us suppose it to be true, as was heretofore believed,
that double power of steam requires double fuel to produce it; then by the
scale, if 212 degrees of heat give power equal to 15 pounds, and require
1 bushel of fuel, 242 degrees giving 30 pounds power, will require 2 bushels,
and so on to the end of the scale. 424 degrees of heat, double 212, would
require 128 times the fuel to produce it, which is quite absurd. It is much
easier to conceive, that double heat would produce 128 times the power.
Although double fuel will not produce near double heat, yet it is easy to
conceive, that it may give
*See the Repertory of Arts, vol i. series 2.
Although experiments have been made with great care and accuracy, to ascertain the fact as to the rapidity of the increase of the power of steam, compared to the increase of heat in the water, yet I find no attempts made to apply the principle, nor even a suggestion to that effect, in any of the books that have ever fallen into my hands. But the result drawn by Dalton cannot be true, because his scale continued, the increase of the elasticity by the increase of heat, would entirely cease before the power could be augmented sufficiently to produce the effects which have been produced.
10
such heat, as will produce 16 times the power. We should
observe also how rapidly the proportionate quantity of heat diminishes,
which is required to be added, in order to gain power, as the water rises
in temperature.*
SCALE OF EXPERIMENTS.
Temperature of the water Degrees |
Elastic power of steam lbs. |
Proportional heat to be added to the temperature which the water may be in, to double the power |
| 10 | .11 | 3 |
| 40 | .23 | .75 |
| 70 | .46 | .42 |
| 100 | .93 | .30 |
| 130 | 1.87 | .23 |
| 160 | 3.75 | .19 |
| 190 | 7.5 | .16 |
| 220 | 15 | .14 |
| 250 | 30 | .12 |
| 280 | 60 | .11 |
| 310 | 120 | .09 |
| 340 | 240 | .085 |
| 370 | 480 | .08 |
| 400 | 960 |
By this scale of experiments, it appears, that when the water was in the temperature of 10 degrees, the elastic power of the steam was but
11/100 parts of 1 pound to the inch, and the heat required
to be tripled, by adding 30 degrees to double the power. But when the heat
was raised to 220 degrees, the power was 15 pounds, and required but 14/100
parts of the heat to be added, or 30 degrees to double the power to 30 pounds.
Here 30 degrees increase of heat gained 15 pounds, whereas in the low temprature
of 10 degrees, the 30 degrees added, gained but 12/100 parts of 1 pound.
When the
*See the American edition of the Encyclopedia, vol
17.
11
water is heated to 370 degrees, and the power of steam raised to 480 pounds to the inch, it requires but 30 degrees additional heat, or 8/100 parts of the heat of the water, to be added to gain 480 pounds more power. If the reader has faith to believe thus far, he is ready to ask, by what unaccountable law of nature is the elastic power of steam produced in this ratio, so variable as to the quantum of additional heat, required to gain a given quantity of power? for hy the last addition of 30 degrees of heat in this scale, we gain 4363 times as much power as by the first addition.
I answer, it is enough for us to know by experience that it is so, to enable us to avail ourselves of the application of the principles. It clearly points out to us the great gain tobe had by working with high temperatures; for if doubling the consumption of fuel produces six. teen times the bulk and power of steam, it enables us to produce eight times the effect, with equal quantities of fuel, and I am inclined to believe, that the application of the principles may be improved to that extent. But we should not rest satisfied, until we are able to assign philosophical reasons why it is so, which leads us to treat of heat.