The Atlantic Monthly, Volume V, Number 29, March, 1860

V >> Various >> The Atlantic Monthly, Volume V, Number 29, March, 1860

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"Harass her not; thy heat and stir
The greater coyness breed in her:
Yet thou may'st find, ere Age's frost,
Thy long apprenticeship not lost,
Learning at last that Stygian Fate
Supples for him that knows to wait.
The Muse is womanish, nor deigns
Her love to him who pules and plains;
With proud, averted face she stands
To him who wooes with empty hands.
Make thyself free of manhood's guild;
Pull down thy barns and greater build;
The wood, the mountain, and the plain
Wave breast-deep with the poet's grain;
Pluck thou the sunset's fruit of gold;
Glean from the heavens and ocean old;
From fireside lone and trampling street
Let thy life garner daily wheat;
The epic of a man rehearse,
Be something better than thy verse,
Make thyself rich, and then the Muse
Shall court thy precious interviews,
Shall take thy head upon her knee,
And such enchantment lilt to thee,
That thou shalt hear the lifeblood flow
From farthest stars to grass-blades low,
And find the Listener's science still
Transcends the Singer's deepest skill!"

SCREW-PROPULSION:

ITS RISE AND PROGRESS.

The earliest conception of an auxiliary motive power in navigation
is contemporaneous with the first use of the wind; the name of the
inventor, "unrecorded in the patent-office," is lost in the lapse of
ages. The first motor was, undoubtedly, the hand; next followed the
paddle, the scull, and the oar; sails were an after-thought, introduced
to play the secondary part of an auxiliary.

Scarce was man in possession of this means of _impressing_ the wind, and
resting his weary oar, than, scorning longer confinement to the coast,
he boldly ventured upon the conquest of the main. Under the same
impulse, the tiny skiff, in which he hardly dared to quit the river's
bank, was enlarged, and made fit companion of his distant emprise. These
footprints of the infant steps of navigation may all still be traced
among the maritime tribes of the Pacific.

From that period sails became the chief motor, and the paddle and the
sweep auxiliaries,--which position they still hold to some extent, even
in vessels of considerable burden. But as the proportions of naval
architecture enlarged, these puny instruments were thrown aside;
although the importance and necessity of some such auxiliary in the
ordinary exigencies of marine life have always been felt and it has long
been earnestly sought.

From the first successful application of steam to navigation--by Fulton,
in 1803--it was supposed to be the simplest thing in the world to
provide ships with an auxiliary motor; but the result has shown the
fallacy of this conception.

For more than twenty years steam-navigation has advanced with giant
strides, overstepping several times the limits which science had
assigned it; but the paddle-wheel, by which the agency of steam has
been applied, forms so bad an alliance with canvas, and supplies so
indifferently the requirements of a man-of-war, that it has been
impossible by this intermediary to render steam the efficient coadjutor
of sails; and it is for this reason that steam so speedily took rank
as a primary motor upon the ocean; for, in all the successful marine
applications of steam by means of the paddle, steam is the dominant
power, and sails the accessory, or almost superfluous auxiliary. It is
the screw alone, in some of its modifications, which offers the means of
a successful and economical adaptation of steam to ships of war or of
commerce; for it is susceptible of a more complete protection than, the
paddle, and of an easy and advantageous combination with canvas.

The screw-propeller, in fact, has assumed so important a part in all
naval enterprise, that it may not be without interest to trace briefly
its rise and progress to the consideration it now commands, and
to review, in general terms, the various experiments by which the
screw-frigate has been brought to its present high state of efficiency,
excelling, for purposes of war, all other kinds of vessels.

As early as 1804, John Stevens, of Hoboken, New Jersey, engaged in
experiments to devise some means of driving a vessel through the water
by applying the motive power at the stern, and with a screw-propeller
and a defective boiler attained for short distances a speed of seven
knots; and it is surprising, that, with the genius and determination so
characteristic of his race, he should have abandoned the path on which
he appears to have so fairly entered.

Within the last half-century numerous attempts of a similar character
have been made in Europe and America; but although many of the
contrivances for this purpose were exceedingly ingenious, and the
success of some of the experiments sufficient, one would suppose, to
excite the interest of the public and encourage perseverance in the
undertaking, yet in no instance were they followed by any practical and
useful results until the year 1836, when both Captain Ericsson and
Mr. F. P. Smith so fully demonstrated the speed and safety with which
vessels could be moved by the screw-propeller, as to convince every
intelligent and unprejudiced mind of the importance of their inventions,
and immediately to attract the attention of the principal naval powers
of the world.

Captain Ericsson is a native of Sweden, but for some years previous to
1836 he had resided in England, where he had become known as an engineer
and mechanician of distinguished ability.

In July, 1836, he took out a patent in England for his method of
propelling vessels; and during that year the results of his experiments
with a small boat were so satisfactory, that in the following year he
built a vessel forty-five feet long, with eight feet beam, and drawing
three feet of water, called the Francis B. Ogden, in compliment to the
gentleman then consul of the United States at Liverpool, who was the
first person to appreciate the merits of his invention, and to encourage
him in his efforts to perfect it. This vessel was tried upon the Thames
in April, 1837, and succeeded admirably. She made ten knots an hour, and
towed the American ship Toronto at the rate of four and a half knots an
hour; and in the following summer, Sir Charles Adam, one of the Lords
of the Admiralty, Sir William Symonds, the Surveyor of the Navy, and
several other scientific gentlemen and officers of rank, were towed by
her in the Admiralty barge at the speed of ten miles an hour.

Notwithstanding this demonstration of the powers of his vessel, Captain
Ericsson did not succeed in exciting the interest of any of the persons
who witnessed the performance; and it seems almost incredible that no
one of them had the intelligence to perceive or the magnanimity to admit
the importance of his invention. But, fortunately for Ericsson and the
reputation of our country, he soon after met with Captain Stockton, of
the United States navy, who at once took the deepest interest in
his plans. The result of one experiment with Ericsson's steamer was
sufficient to convince a man of Stockton's sagacity of the immense
advantages which the new motor might confer upon the commerce and upon
the navy of his country, and forthwith he ordered an iron steamer to be
built and fitted with Ericsson's propeller. This vessel was named the
Stockton, and was launched in July, 1838, and, after being thoroughly
tested and her success demonstrated, she was sent under sail to the
United States in April of the next year, and was soon after followed by
Captain Ericsson; when, in consequence of the representations of Captain
Stockton, the government ordered the Princeton to be built under
Ericsson's superintendence, and to be fitted with his propeller.

The Princeton, of 673 tons, was launched in April, 1842, and her
propeller, of six blades, of thirty-five feet pitch, and of fourteen
feet diameter, was driven by a semi-cylinder engine of two hundred and
fifty horse-power, and all her machinery placed _below_ the water-line.
Her smoke-stack was so arranged that the upper parts could be let into
the lower, so as not to be visible above the rail; and as the anthracite
coal which she used evolved no smoke, she could not, at a short
distance, be distinguished from a sailing-ship.

Her best speed under steam alone, _at sea_, was 8.6, and under sail
alone, 10.1 knots; her mean performance under steam and sail, 8.226; and
considering the imperfect form of boiler employed, and the small
amount of fuel consumed, it may be doubted if this has since been much
excelled. She worked and steered well under canvas or steam alone, or
under both combined; was dry and weatherly, but pitched heavily, and was
rather deficient in stability.

[Footnote: For a particular account of the Princeton, by B. F.
Isherwood, U. S. N., see _Journal of the Franklin Institute_ for June,
1853. Taking everything into consideration, the Princeton was a most
successful experiment, and, in her day, the most efficient man-of-war of
her class. By her construction the government of the United States had
placed itself far in advance of all the world in the path of naval
improvement, and it is deeply to be regretted that it did not avail
itself of the advantage thus gained; that it did not immediately order
the construction of other vessels, in which successively the few defects
of the Princeton might have been corrected; that it did not persist in
that path of improvement into which it had fortunately been directed,
instead of suffering our great naval rivals to outstrip us in the race,
and compel us at last to resort to them for instruction in that science
the very rudiments of which they had learned from us.]

The success of the Princeton was followed by the general adoption in
America of the screw-propeller. When Ericsson left England, he confided
his interests to Count Rosen, who, in 1843, placed an Ericsson propeller
in the French frigate Pomone, and soon afterwards the British Admiralty
determined to place it in the Amphion. Not only was the performance of
these vessels highly satisfactory, but they were the first ships in the
navies of Europe in which the great desideratum was secured of placing
the machinery below the load-line. Ericsson's propeller having been the
first introduced into France, it was generally adopted; but afterwards,
in consequence of the accounts of Smith's screw received from England,
it underwent various modifications.

Such was the result of Ericsson's labors; it now remains to relate the
success of Smith. The efforts of either had been sufficient to have
secured to navigation the inestimable advantages of screw-propulsion,
but their rivalry probably hastened the solution of the problem.

In May, 1836, Mr. F. P. Smith, a farmer of Hendon, in England, took out
a patent for his screw-propeller, and exhibited some experiments with it
attached to a model boat, and in the following autumn built a boat of
six tons' burden, of ten horse-power, and fitted with a wooden screw.
This vessel was kept running upon the Thames for nearly a year, and her
performance was so satisfactory, that Mr. Smith determined to try her
qualities at sea; and in the course of the year 1837, he visited in her
several ports on the coast of England, and proved that she worked well
in strong winds and rough water.

These trials attracted much attention, and at last awakened the interest
of the Admiralty, who requested Mr. Smith to try his propeller on a
larger vessel, and the Archimedes, of ninety horse-power and 237 tons,
built for this purpose, was launched in October, 1838, and made her
experimental trip in 1839. It was thought that her performance would be
satisfactory, if she could make four or five knots an hour; but she
made nearly ten! In May, 1839, she went from Gravesend to Portsmouth,
a distance of one hundred and ninety miles, and made the run in twenty
hours.

In April, 1840, Captain Chappel, R. N., and Mr. Lloyd, Chief Engineer of
Woolwich Dockyard, were appointed by the Admiralty to try a series
of experiments with her at Dover. The numerous trials made under the
superintendence of these officers fully proved the efficiency of the new
propeller, and their report was entirely favorable.

The Archimedes next circumnavigated Great Britain under command of
Captain Chappel, visiting all the principal ports: she afterwards
went to Oporto, Antwerp, and other places, and everywhere excited the
admiration of engineers and seamen.

Up to this period, the British engineers were nearly unanimous in the
opinion that the use of the screw involved a great loss of power, and
they had concluded that it could not be adopted; but it was impossible
any longer to resist the impressions made on the public by the
demonstration which had been given both by Smith and Ericsson; and
although the engineers were still unwilling to admit the screw to a
comparison with the paddle, it was evident that their first conclusions
regarding it were erroneous, and thereafter it was viewed by them with
less disdain and spoken of more hopefully. One of the great objections
by engineers to the use of the screw was their inability, at the time of
its introduction, to construct properly a screw engine,--that is to say,
a direct-acting horizontal engine, working at a speed of from sixty to
one hundred revolutions per minute,--all their experience having been in
paddle-wheel engines, working from ten to fifteen revolutions per
minute. The peculiar mechanical details required in the screw engine,
the necessity for accurate counterbalancing, etc., were then unknown,
and had to be learned from a long succession of expensive failures. In
England, the first machines applied to the screw were paddle-wheel
engines, working it by gearing; there were consequently lost all the
advantages of the reduced cost, bulk, and weight of the screw engine
proper, including, for war purposes, the important feature of its being
placed below the water-line. At first, the screw had not only to contend
with physical difficulties, but to struggle against nearly universal
prejudice; many inventors had succumbed to these obstacles, and
therefore too much applause cannot be bestowed upon those who,
unsustained by public sympathy, and in defiance of a prevailing
skepticism, maintained their faith and courage unshaken, and gallantly
persisted in their efforts, until crowned with a world-wide success.

Ericsson, before interesting himself with the screw, was, as has been
seen, an engineer and mechanician of distinguished ability; whereas
Smith, in commencing his new vocation, had all to acquire but his first
conception. Ericsson could rely upon the fertility of his own genius,
was his own draughtsman, and designed his own engines, accommodating
them to the new propeller by dispensing with gearing, and adapting
them to a speed of from thirty to forty revolutions,--a great and bold
advance for an initiative step. Smith, on the contrary, not being an
engineer, had to intrust the execution of his plans to others, whose
knowledge of construction was in the routine of paddle-wheel engines;
and this accounts for the fact, that all the earliest British
screw-steamers were driven by gearing. This want of mechanical resources
on the part of Smith added to the difficulties of his career; but his
resolution and perseverance rose superior to all obstacles, and carried
him to the goal in triumph. Briefly, then, these were the respective
merits of Smith and Ericsson, in the introduction of screw-propulsion;
and it is much to their honor, that, throughout their career, no
narrow-spirited jealousies dimmed the lustre of a noble rivalry.

Such was the origin of the new motor,--the mighty engine by which
armadas are marshalled in battle-array, the burdens of commerce borne to
distant marts, the impatient emigrant transferred to the promised land,
and by which the breathings of affection, the pangs of distress, and the
sighs of love are wafted to far-off continents.

In consequence of the success of the Archimedes, the Admiralty ordered
the Rattler to be fitted with a screw, and it was no small satisfaction
to find that her double-cylinder engines could be easily adapted to the
new propeller. She is of 888 tons, and two hundred horse-power, and was
launched in the spring of 1843, being the first screw-vessel in the
British navy.

In the course of the two succeeding years, she was tried with a great
many different screws, and numerous experiments were made to discover
the length, diameter, pitch, and number of blades of the screw, most
effective in all the various conditions of wind and sea. A screw of two
blades, each equal to one-sixth part of a convolution, and of a uniform
pitch, was, on the whole, found to be the most efficient, and this is
the screw now adopted in most of the ships of all classes in the British
navy.[1]

A propeller of very different construction, which had given great
results in a ship of the Peninsular and Oriental Steamship Company, and
was afterwards exhibited in the docks at Southampton, here claims a
passing notice. This propeller is so constructed as to enable the
engineer to regulate the speed of the piston; for _the pitch of the
screw can be increased or diminished at pleasure_. Thus, with a fair
wind, by increasing the pitch, without increasing the revolutions, the
full power of the engine is effectually exerted in driving the ship,
instead of consuming fuel in driving the engine to no purpose; and with
a headwind, by diminishing the pitch, the engines are made to do their
utmost duty; and when the ship is under canvas only, the blades of the
propeller may be placed in line with the stern-post, and thus offer
little resistance. Another advantage claimed for this propeller (known
as Griffith's) is, that, in the event of breaking a blade, it may be
readily replaced by "tipping the ship"; which method merits careful
consideration by engineers, as does especially every new propeller which
promises a more perfect alliance with canvas.

To resume the narrative,--the speed of the Rattler was afterwards tested
by a trial with the Alecto, a paddle-wheel steamer of equal power,
built from the same moulds; and the result was so favorable, that the
Admiralty ordered the construction or conversion of _twenty-three_
vessels as screw-steamers, and thus was laid the foundation of the
present formidable steam-navy of England.

The superiority which has been asserted for the Princeton was
established during the Mexican War by her performance before Vera Cruz
as a blockading ship of unprecedented efficiency, which, having been
displayed under the admiring observation of a British squadron, tended
more than any other single event to confirm the Admiralty in the
conclusions to be drawn from the experiments just related, and to decide
them in the adoption of the screw as the best auxiliary of sail, the
best mechanical motor upon the ocean. Thus did England, in embracing at
once the practical demonstration of the Princeton, display that forecast
by which she won her ascendency at sea, and the vigilance with which
she maintains it; whilst our own government awaited, in unbecoming
hesitation, the results which England's more extended trials with the
screw might develop.

This cautious policy, rather than the bold and liberal course which the
maritime genius of the country demands, condemned us for long years to
inaction, until, at length, the absolute necessity for the renewal of a
portion of our naval force produced the "Minnesota" class of frigates.
Although they developed little that was absolutely new, they are very
far from being imitations; but in model, capacity, equipment, and above
all in their armament, they have challenged admiration throughout the
world, and called from a distinguished British admiral in command the
significant declaration, that, until he had seen them, he had never
realized his ideal of a perfect man-of-war.

A leading idea in the conception of these ships was to reduce the number
of gun-decks from two and three to a single deck, and, consequently, the
space in which shells could be lodged. This is a consideration which
must, it is believed, sooner or later govern in naval construction;
although France and England, long accustomed to measure the power of
ships by the number of gun-decks, may be more slow in following our lead
in this respect than in imitating the increased calibre of our ordnance.

The new classes of steamers preparing for sea, of which the Hartford and
Iroquois are types, promise to be most efficient ships, and to reflect
much credit upon our naval authorities for their bold, yet judicious
departure from traditions which had long hampered the administration of
this important branch of the public service. Although the reflection is
seldom made, it is nevertheless true, that much of the reputation
enjoyed and of the influence exercised by the United States is due to
the efficiency of her navy; and if these are to remain undiminished,
then it is of the utmost consequence that the national ships should
always represent the highest advancement of nautico-military science.

[Footnote 1: A series of experiments with the screw were made on board
the Dwarf in 1845, and on board the Minx in 1847 and 1848, but the
results did not materially differ from those previously obtained. In the
Rattler, Dwarf, and Minx twenty-nine different propellers were tried.]

The efficiency of the screw having been demonstrated, it was seen that
the next requirement for a war-steamer was to place her machinery below
the waterline; and hence arose a demand for an entirely new description
of engines, which it was clear would make a great change in all the
labors of the engineer and machinist. Such change it was evident would
greatly enhance the risk of failure, and therefore it was determined by
the Admiralty to insure success in this very difficult task by enlisting
all the best talent of the country. Accordingly, for the twenty-three
ships an equal number of screw engines were ordered; and as with the
constructors, so with the engineers, each was required to comply
with certain conditions, yet each was permitted to put forth his own
individuality, and each has illustrated his views of what was required
by a distinct plan of engine.

The wise and liberal action of the British Admiralty, which faltered at
no expense, and made trial of every improvement in machinery that gave
assurance of good performance and promised in any way to increase
the efficiency of the fleet, produced no less than fourteen distinct
varieties of the screw engine. Among them all, Penn's horizontal
trunk-engine appears to be the favorite, and had performed so well
in the Encounter of fourteen guns, the Arrogant of forty-six, the
Imperieuse of fifty, and the Agamemnon of ninety, that two years ago
it had been placed, in about equal proportions of two hundred, four
hundred, six hundred, and eight hundred horse-power, on board of forty
ships and many smaller vessels of the British navy; it had fulfilled all
the promises made for it, without in any instance requiring repairs.
These engines comply with all the conditions reasonably demanded in
the machinery of a man-of-war; they lie very low, and the fewness and
accessibility of their parts leave scarcely anything to be desired;--a
lighter, more compact, or more simple combination has yet to be
conceived.[1]

In all the ships above referred to the connection of the engines is
direct, and many of them are driven at rates varying from fifty to
seventy-five revolutions. This point is dwelt upon because it is
observed that many engineers find difficulty in freeing themselves from
early impressions made by long-stroke engines, express apprehensions at
fifty and sixty revolutions, and stand ready to obviate the difficulty
by gearing,--which it is hoped may not henceforth be adopted in our
national ships. Geared engines are much heavier than those of direct
connection, and occupy more space,--a great consideration in ships where
room for fuel is in such demand, besides making it more difficult to
place them below the waterline,--a consideration which in men-of-war
should be regarded of paramount importance, as the engines of a
war-steamer should be as secure from shot as her magazine. Experience
has shown that the apprehensions entertained from the quick stroke of
direct engines were without foundation; and that, in auxiliary ships,
with a properly modelled propeller, there will be no necessity for a
very high speed of piston.

The form of engine generally adopted with great success in the later
screw-ships.

[Footnote 1: "Its large amount of friction" is an objection often
speciously urged against the trunk-engine, although the friction diagram
shows it to be actually less in this than in most other engines.] of
the United States navy is the "horizontal direct action," with the
connecting-rod returning from a cross-head towards the cylinder;
these engines make from sixty to eighty revolutions per minute.
The steam-valve is a packed slide with but little lap, and the
expansion-valve is an adjustable slide working on the back of the
steam-valve. The boilers are of the vertical water-tube type, with the
tubes above the furnaces, and are supplied with fresh water by tubular
surface-condensers, which, together with the air-pumps, are placed
opposite the cylinders.

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