Francis Lieber.

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does not show at all what proportion of that work has to be expended in overcoming
the friction of the engine itself. It is ascertained by the use of a little machine called an
" indicator," devised by "\Vatt, and since his time greatly improved, especially by Mr.
Richards.

By taking the mean pressure per square inch on the piston throughout the stroke
(deduced from the indicator card), and multiplying it by the area of the piston, and by the
mmber of feet passed through by it in a minute, we should find the number of foot-
pounds of work done by the engine per minute; and this, divided by 33,000, would give
the indicated horse-power.

" Duty" is a measure of power used only for pumping engines, and differs from
horse-power in being entirely independent of time. It is the number of foot-pounds of
net work resulting from the consumption of a given quantity of coal, usually either a
bushel of 94 Ibs. or a hundred weight. At the beginning of this century the maximum
duty that had been attained by any Cornish engine was 20 millions of f pot pounds per cwt.
of coal, but six times that duty has since been occasionally obtained. In these engines,
it is the actual net work done which is taken into account; the duty would be 20 or 25

For engines whose power can only be measured by the indicator, the standard of
economy is the number of Ibs. of fuel used per hour per indicated hor,se-power. In fac-
tories where "dross" is used as fuel, with horizontal engines and Cornish boilers, and
where n<3 means are taken to insure economy, we have known 15 to 20 Ibs of fuel burned
per indicated horse-power per hour. In marine engines and other cases where the best
coal only is used, and where high pressures, surface condensation, and compound cylin-
ders are employed, the consumption of fuel is often as low as 2 pounds.

The theory of a "perfect heat-engine," which should return in mechanical work
(see FORCE) the greatest possible amount of the heat supplied to it, is considered under
THERMODYNAMICS. For other points, see articles BOILER, SAFETY VALVE, and SCREW
PROPELLER, as well as STEAM, also the articles STEAM-ENGINE and MARITIME Cox-
VEYANCE in Information for the People. For advanced students, prof. Rankin's Steam-
Engine (GrifHn) is the best, with Mr. Cotterill's excellent Notes on the Theory of the
Steam-Engine (Spon.)

STEAM-HAMMER, THE, has doubtlessly contributed more than any other mechanical
invention of modern times in developing the wonderful resources of the iron trade, and
is still looked upon as a marvel of engineering skill and ability. The first idea of a
steam-hammer appears to belong to James Watt, the great father of engineers, and was
patented by him iu 1784. In 1806, a William Deverell, described as "an engineer of

Stea. 800

Suny," also took out a patent for a steam-hammer; hut in neither case does it appear
that steam-hammers were actually constructed. From this time till 1837, the idea seems
to have been entirely lost sight of, when it was again taken up by Mr. James Nasmyth, of
the Bridgewater foundry, Patricroft, near Manchester, as the result of an application made
to him by Mr. Francis Humphreys, engineer to the Great Western Steamship company,
>vho had been unable to induce any forge-master to undertake the forgings required fur
the paddle-shafts of the Great Britain steamship, then in course of construction. Mr.
Nasmyth sent a sketch of his hammer plan to Mr. Humphreys, who, along with Mr.
Brunei and others, heartily approved of the scheme, but in consequence of an alteration
being made 'to. the propelling arrangement of the great ship, the paddle-shaft was not
required, and the hammer was not then constructed. The scheme was offered to many
of the large forge-masters and engineers; but while all seemed to admire the idea, they
failed to appreciate its value and importance, and the hammer remained a mere sketch.
in Mr. Nasmyth's "scheme-book" till 1842, when, in December of that year. Mr. Nas-
myth secured a patent for his invention, and the first steam-hammer was made in accord-
ance with his plan at the Bridgewater foundry early in 1843, but although considered
by some as an improvement upon the old " helves" hitherto used for forging purposes,
it was very far from being a perfect or even a marketable tool. The hammer was
workgd by means of an ordinary slide-valve and a long lever, requiring great labor
and constant attention in order to give the blow required; so that some contrivance
was necessary, capable of adjustment, in order to have complete command over the
power of the blow, and that, the instant the blow was struck, the block should rise
again, so that not only no loss of time should ensue, but that the heat in the mass of
iron on the anvil might not be reduced or carried off by the cold face of the block. The
peculiar difficulty of securing a true automatic arrangement will be seen when it is con-
sidered that the instant of percussion must vary with almost every blow that is struck;
for the piece on the anvil becomes thinner and thinner by each succeeding blow, and in
flat bars a blow is first given on the flat side, and then on the edge, the difference in the
fall of the hammer in the two cases being oftentimes several inches; and further, that
the hammer must be under perfect control at all times.

Mr. Nasmyth, after many and protracted trials, failed to produce the motion re-
quired, and, as a consequence, the whole hammer scheme was on the point of being
abandoned. In this dilemma, and during Mr. Nasmyth's absence from the works, his
partner, Mr. Gaskell, applied to their engineering manager, Mr. Robert Wilson, who
afterward became managing partner and successor to Mr. Nasmyth, to endeavor to solve
the problem which had hitherto baffled the skill of Mr. Nasymth. Mr. Wilson took
the matter in hand, and in little more than a week, a motion was invented and attached
to a hammer upon which former experiments had been made, and was at once found to
answer most admirably every condition required. Under the influence of this very
beautiful mechanical motion every variety of blow could be given, from the gentlest
tap to the heaviest blow within the compass of the hammer, and that, too, perfectly
' self-acting in every respect, the long lever and the hard work before referred to being "
now entirely banished. By simply altering the position of the tappet lever by means of
two screws, a blow of the exact force required could be produced and continued so long
as steam was supplied. So completely was the hammer now under control, that it be-
came a favorite amusement to place a wine-glass containing an egg upon the anvil, and
let the block descend upon it with its quick motion; and so nice was its adjustment,
and so delicate its mechanism, that the great block, weighing perhaps several tons,
could be heard playing tap, tap, upon the egg without even cracking the shell, when, at
a signal to the man in charge^ down would come the great mass, and the egg and glass
would be apparently, as Walter Savage Landor has it, "blasted into space." On
Aug. 18, 1848, the first hammer was delivered to Messrs. Hird, Dawson, and Hardy
of the Low Moor iron works, near Bradford, Yorkshire, and gave such satisfac-
tion, that orders fornhis remarkable tool began to flow in from all parts of the country.
The hammer remained in this condition, with the exception of a few minor details,
from 1843 to 1853, when Mr. Wilson (who in the interim had removed to the Low Moor
iron-works) invented, patented, and applied to the hammers at Low Moor and elsewhere
what is called the "circular balanced valve." The Practical Mechanic's Journal for
1855, vol. viii., p. 174, in an article on this invention, says: "The wonders of Mr.
Nasmyth's invention, the steam-hammer, have just received new luster at the hands of
Mr. Wilson, to whom belongs a large portion of the credit attaching to the early prac-
tical development of the beautiful automatic action of this invaluable tool. The special
feature which Mr. Wilson has introduced is his balanced-pressure cylindrical valve, sev-
eral modifications of which we noticed in our pages of June and July last year. Ham-
mers divested of all self-acting apparatus whatever, and fitted merely with a hand-
geared valve of this kind, exhibit an immensely improved action, enabling the workman
to obtain the exact kind of blow he wants under all circumstances. This adjustment
of the hammering force is attained just as effectually as with the simple hand-hammer
of the smith, one stroke giving perhaps a mere touching tap, and the next a blow of the
highest intensity."

In July, 1856, Mr. Wilson returned to the Bridgewater foundry as managing partner
in the firm of James Nasmyth and company, and in September following obtained a pa- -

801 steam .

lout for a bnlanred xlide-vahe, and at once arranged to apply his invention to all hammers
subsequently to he made there, which arrangement continues in operation to the !>
time, His balanced slide-valve, by a most ingenious arrangement, allows the v,>;
it were, to iloat in an atmosphere of steam pressing equally upon it on every side, en-
tirely doing awr.y with all superincumbent pressure upon the (alee, no matter what the
pressure iu the boll. r maybe. The great advantage of this invention will be apparent
when it is stated that hammers are now made or such a size, that, if the valve were not
balanced, a small steam engine would be required to move it.

In June, 18(H, Mr. Wilson patented and introduced another very important im-
provement, popularly known as the double-act ii if) linnd-gear motion. By this arrange-
ment, the steam is admitted as before to raise the piston, and when it has attained tho
required elevation, and at the very moment when about to descend, by slightly in-
creasing the travel of the hand-lever (more than when working single-acting), the s'teaio,
is admitted into the cylinder above the piston, which accelerates and increases the in-
tensity of the fulling Mow and the consequent capacity of the hammer; so much so, that
that which had hitherto been described as a five-ton, hammer is by this double-action
arrangement increased to at least a 12i or 15 ton one.

In 180'2, .Mr. \Vil>on designed and constructed a small hammer suitable for tilting
steel, litted with the balance- valve, double acting, and with an entirely new self-
acting motion (much less complicated than the original one) capable of strking f.va
hundred blows per minute. Then; are many patents for this kind of hammer, which i3
now very largely used in the forging of steel.

One of the largest st<. am-hammers yet constructed is at Perm (a town in the n.e. of
Russia), and is used for the manufacture of large cast-steel guns. It is a 50-ton ham*
mer, made double-acting in the way above mentioned, so as to be equal to a 100-ton,
single-acting one. Its anvil-block is the largest casting ever made, weighing con-
siderably more than 500 tons. It was cast in its place, but upside down, engines being
erected to turn ii over when finished. The metal was melted in 14 furnaces, for which
the blast was provided by three large blowing-engines, all three being especially fitted
up for the purpose. It was several mouths before the casting was cool enough to bo
uncovered and turned over.

STEAM-HEATING. See WARMING AND VENTILATION.

STZAM-ITATK/ATIOIT. When once steam -was known as a moving power, its ap-
plication to navigation was obvious enough: it was even to this purpose that the first
attempt was made to apply it at al! that of Blasco de Garay namely, in the harbor of
Barcelona in 1543. See STEAM-ENGINE. The only surprising thing is, that 30 years
should have elapsed between 1777, when the steam-engine had become in Watt's
hands an eincient power for other purposes, and 1807, the date of Fulton's first voyage
before a really serviceable steam-vessel was produced. The connecting link seems to
be the use of revolving-paddles instead of oars. Wheel-boats propelled by oxen, horses.
or men were known to the Romans, and were used for ferry-boats in modern times.
Some experiments with this mode of propulsion made by Mr. Miller of Edinburgh,
suggested to his friend Mr. Taylor the application of steam as the moving power, and
led to the most decided step in the discovery of steam-navigation previous to the final
success of Fulton.

As early as 1736 Jonathan Hulls had taken out a patent for a tow-boat to be pro-
pelled by a paddle-wheel set in motion by a sort of steam-engine. The project appears
never to have been executed. Besides some experiments on the Seine by comte d'Auxirou
in 1774, and Perier in 1775, the marquis de Jouffroy constructed a steamboat of con-
siderable size in 1782 which navigated the Saone for some time; it was deficient, how-
ever, in power. In America experiments began to be made about 1783 by Fitch ami
Rumsey. Fitch launched a paddle steamboat in 1788 which moved at the* rate of 4 m.
an hour; but, before proceeding far the boiler burst. Rumsey proposed to propel the
vessel by making a stream of water issue with force from the stern; his attempt failed.

The next important experiment was the one above alluded to, by Messrs. Miller and
Taylor. It t<>ok place on a small lake on Mr. Miller's estate of Dalswiuton in Dumfries-
shire. A small engine having 4-in. cylinders of bra>s was prepared, under the superin-
tendence of Mr. Taylor, tutor in Mr. Miller's family, and Mr. Symington, an ingenious
mechanic, and fitted on board a double boat, with a paddle-wheel in the interspace.
The trial took place amid a concourse of hundreds on Oct. 14, 1788, and with perfect
success. Next year Mr. Miller had larger engines titled into a vessel, and tried on the
Forth and Clyde canal, when the vessel moved at the rate of 7 m. an hour. Partly
from caprice, partly from derangement of his affairs. Mr. Miller was diverted from pur-
suing the matter further. But in 1801 Mr. Symington took out a patent for the con-
struction of steamboats, and in 1803 built, the Charlotte Dunda*, to tow vessels on tlia
Forth and Clyde canal. The success seems to have been complete, excepting in one
respect, that the agitation of the water by the paddles was found to wash down tho
banks in an alarming manner. The use of the vessel was therefore given up, and it hy
at Ijock Sixteen for many years.

In the meanwhile, attempts had been making at steam-navigation in America by
Stevens, Livingston, and others. Robert Fulton, another American, had thought at
U. K. XIII. 51

Steam.
Stearns.

steam as a motive-power for vessels as early as 1793. Traveling into Scotland he visited
the unfortunate Cliarlotte Dundas, and obtained drawings of the machinery. Return-
ing to America with one of Boulton and Watt's engines of 20 horse-power, he, in con-
junction with Livingston, built a vessel called the Clermont, at New York, and in 1807
made the first really successful voyage by steam from New York to Albany, up the
Hudson. The vessel sailed 110 m. in 24 hours, against stream and wind. Fulton has
thus indisputably the honor of having first proved ti.e practical utility of steam-naviga-
tion. Yet nothing but perseverance seems to have been wanting to crown tlie experi-
ments of Miller, Taylor, and Symington with equal success. Four year? later, lyil,
Henry Bell of Glasgow, who had witnessed the experiments on the canal in 17S9, ::nd had
accompanied Fulton on his visit to the CJtarlotte JUtrndas, started a steamboat, the Comet,
on the Clyde, and was thus the father of steam-navigation in Britain.

In 1815 a steamboat made a passage from Glasgow to London, and in 1818 one plied
from New York to New Orleans; it was not till 18'<!0 th.it steam-packi ts were established
between Holyhcad and Dublin. 1838 was a memorable year in the history of steam-
navigation. The steamer Sinus sailed from Cork on April 4, the Great Vt'ciffeni from

'

Bristol on the 8th of the same month ; both arrived at New York on the 23d, the Sin'ta
being only twelve or fifteen hours before the other. The passage is now often made
from New York to England in eight or nine days. Steam- vessels are now to be found
on all seas and lakes and navigable streams. War-steamers have taken the place of the
old ships of the line; and except for tlie transport of heavy goods to long distances,
steam bills fair to supersede the use of sails. The maximum speed yet attained by steam-
vessels is 20 m. an hour; the ordinary rate 8 to 15 miles.

The steam-engine employed to propel a vessel docs not differ essentially from any
other; but some modifications are necessary to suit the special circumstances under which
they work. In ships of war, the cylinders are generally placed horizontally, and the
whole machinery kept below the level of the water-line; in merchant vessels, vertical
engines are more commonly used, with the cylinders inverted, placed right above the
propeller-shaft. For working paddle-wheels, oscillating engines were, on ihe whole, the
most common. See STEAM- ENGINE; PADDLE-WHEEL; SCKEW-PKOPELLER.*

STEAM PUMP. The simplest steam pump is the siphon pump, which nets upon
the principle of the tromp (q.v.), except that the motion of steam causes the motion of
the water, while in the tromp the motion of the water propels the air. A tube throniih
which the steam is forced enters a hollow globe to a little beyond its center. On either
side of this tube are openings into the globe for the entrance of water. These openings
are much larger than the steam pipe. Opposite the latter is the exit tube for the mixed
steam and water, having a trumpet shape and a length of about once and a half tin.es
the diameter of the globe. The rush of steam across the semi-diameter of the globe and
through this funnel produces exhaustion in the lateral halves of the globe, into which
spaces the water is forced by the external pressure of* the air. The first direct ading
piston pumps were probably invented by Mr. H. R. Worthingtou of New York, while
making experiments for canal steam navigation in 1840. He patented a steam pump for
feeding marine boilers in 1844. The steam cylinder was fed through a pipe which had a

* On the conflicting claims to the merit of this invention, we may here note, in addition to what is
said under the head of screw-propeller, that the application of the screw to the propulsion of vessels
ivell known to have been triedat least before the middle of the 18th ceiituiy. In i he i raite ae A a vire
by Boueuer (Paris, 1746). it is stated that " revolving arms like the vanes of a windmill were tried for
the propulsion of vessels." In 1751 Daniel Bernouilli, the famous mathematician, in his hecued
frOwrages Curieux describes and gives drawings of the screw-propeller. In 1770 James Unit men-
tions a screw-propeller in a letter to Dr. Small, uho replies that he had tried it. In 1 , .u D. BusnneU.
an American, in an account of a sub-marine vessel, describes a screw-propeller for moving it. In 18
J. Stevens tiled at New York a vessel fitted with a screw-propeller driven by a steam-engine made Ly
Boulton and Watt This appears to be the first attempt at propulsion by tlie screw with steam us a
moving power Col Beaufoy has described a spiral oar or screw -propeller, with two sj iral runs fixed
on arms, which he had seen used in China about the year 1780. Since the beginning of the present
century several hundred patents have been taken out for screw-propellers, and it would be a hopeless
task to try to allot to the different claimants their due shares of merit. Hard and costly experience
mere "trial and error" have contributed more to the present perfection of the screw than any recent
"inventions." The name most widely known in connection with the introduction of the screw-pro-
peller is that of Mr (afterward sir) Francis Pettit Smith, a farmer near London, who took out a pate
In May. 1836. for a screw-propeller. This gentleman, who was by no means the first who tried to get
the screw into use, was fortunate enough to obtain the assistance of influential capitalists, and i
various trials on a small scale, he fitted up the Archimedes, a regular sea-going vessel. The complete
guccess of this the first real trial on a large scale, gave to Mr. Smith a position which he had wel
earned not by his invention or improvement of the screw-propeller, but by demonstrating t
world on a large scale its capabilities. Other inventors were before him in point of time, but most ot
them confined their operations to trials of models, or. at most, to small boats fitted with screws whu
were driven by hand. Mr. Robert Wilson made and exhibited working models of a vessel propelled

the introduction and improvement of the screw-propeller; but as sir F. P. Smith, aided by his moneyed
associates was the first to put the screw into a big ship, and boldly go to sea in her. the world \v
continue to give him credit for introducing the screw-propeller into actual use, and sometimes, but
with less justice, he will get credit for having invented it.

OAO Steam.

Steams.

valve at the other end within the boiler. To this valve there was adjusted a float which
controlled the supply of steam, which extended the cylinder through a tlide valve which
was acted upon by a spring controlled by the motion of the piston. The present Worth-
:i and Baker pu M ip was evolved from this apparatus. It is a combination of pump
and steam cylinder, driven by direct action and without intervention of fly-wheel or any
appliance for producing rotary motion. The steam cylinder has the usual arrangement
for the entrance and exit of steam, and the rod and piston is attached to a plunger of a
double acting pump. At the middle of the piston rod, between the pump and steam
cylinder, there is attached an arm which in passing to and fro strikes the lung end of a
lever, which changes the steam valves so as to alternately admit steam on one side or the
other of the piston. Various improvements have been made to control the action of the
slide valve. One method is the employment of a secondary cylinder and piston, to which
steam is admitted by a sub-valve, acted upon by the main piston, near the end of the
stroke. Another method is the employment of a fly-wheel. We will first mention those
pumps having an attached crank and Gy wheel. Of these an example is furnished by
the Eclipse steam pump, made at Pittsbiirg. Penn. The crank-shaft actuates a rocking
lever, which moves the slide controlling the admission and exhaust of steam. The Clay-
ton pump, made at Brooklyn, N. Y., has a yoke which couples the piston and pumping
rods, and answers for the support of the crank-shaft journal. One end of the shaft, by
suitable attachments, controls the valve, while the other supports the fly-wheel. These
fly wheel pumps have the advantage of a perfect control of tlie steam valve. The direct
acting pumps have been the su'-ject of many inventions, the principal object sought being
the arrest of the piston at any rate of speed at a proper distance from the cylinder head.
This has been accomplished by various devices. We have not space to describe the dif-
ferent forms of apparatus, but will mention the following as good examples: Knowles's
steam pump, which employs an auxiliary piston-valve or chest-piston, which hus a recip-
rocating ami rotary motion, which imparts motion to the main valve; Blake's steam
pump, in which both the main and the auxiliary valves are plain, Hat slide-valves, the auxil-
iary valve being a continuation of the ports of the main cylinder, and therefore forming
a movable valve-seat; the Cameron steam pump, in wla'ch the steam-piston, at the end of
the stroke, acts upon valves at either end of the cylinder, alternately admitting and
exhausting steam; the isochromal steam pump, made at Hamilton, Ohio, which has a
governor to regulate the strokes of the piston; and the National steam pump, in which
the valve gear consist^ of a main piston-valve, doing the work of an auxiliary piston, the
valve slum performing the office of an auxiliary valve.

STEARIC ACID A.ND JTE AEINE. The composition of stearic acid is represented by
the for:nul;i CasMssOaJiO; I'm acid heingoneuf the solid fatty acids repn^envd by (he
general formula C m H_iOt,HO. It exi-ts as a glyceiide (stearine) in most fats, and is
especially abundant in the move solid kin Is, s icli as muttun-suet. It is readily obtained
bv saponifying suet, an 1 decomposing the hot solutio i of the soap by tartaric acid.
T : oily acids which are thus liberated are compressed between hot plates, by which