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results such wheels were fitted to many vessels, including H.M.S. " Medea,'*
which was the largest war steamer then under construction: she was
launched in 1833. The "Medea" was 179-4 ft. long, 42 ft. broad over
sponsons, and 835 tons burden; her wheels were 24 '5 ft. diam., with floats
5 625 ft. long by 4 5 ft. broad, and are probably represented by this model.

954. Feathering paddle-wheels (working). (Diam. 17 in. and
11 in.) Presented by Messrs. Bullivant & Co., 1902.

N. 1880-1..

This wheel was adopted by John Seaward after he had seen a similar
arrangement in use on a French steamer in 1833, and which he was informed
was the invention of Fra^ois Cave of Paris. The owners of the patent
rights in the Galloway or Morgan wheel instituted an action, but it was
decided that Seaward's construction was not an infringement of Galloway's
patent.

The floats are carried by shafts turning in the rings of the wheel, and
are feathered by rods that connect a bracket on the back of each float to a
strap on a fixed eccentric sheave secured to the vessel's side. In one model
the strap is driven round by a strengthened feathering rod that acts as a
lever ; in the other, all of the rods are strengthened so as to assist in this
work. In Cave's original wheel, a drag-link attached to an arm on the strap
did this driving.

u 6773. T



322

955. Feathering paddle-wheel (working). (Diam. 17 in.)
Presented by Messrs. Bullivant & Co., 1902. N. 1889.

This wheel was brought out by John Seaward in 1835, and closely
resembles No. 954, but has a crank-pin adjustable by a screw, instead of an
eccentric sheave, for feathering the floats. In this form it only differs from
Morgan's in having the crank-pin outside instead of inside the wheel. This
difference, however, greatly improved the construction, and all modern
feathering wheels are so fitted (see Nos. 816 and 819).

956. Feathering paddle-wheel (working). (Diam. 18 in.)
Presented by Messrs. Bullivant & Co., 1902. N. 1879.

This construction of wheel was adopted by Messrs. Seaward and Capel in
1850.

Instead of a crank- arm on the end of each float shaft Mr. Seaward in
1835 substituted a bracket bolted on to the float. The feathering rods are
moved by a ring on a disc, the eccentricity of which is adjustable by a screw.

957. Feathering paddle-wheel (working). (Diam. 11 '5 in.)
Presented by the Commissioners of Patents, 1859. N. 141.

This modification of Morgan's wheel was patented by Mr. J. P.
Holebrook in 1838, and was an attempt to simplify and strengthen the
construction.

The internal crank-pin is brought to one side of the wheel, although still
within it ; the long feathering rods are replaced by a large rigid frame, which
is connected to toggle links that connect adjacent floats, and thus feather
them in pairs. The wheel combines the large feathering ring of Buchanan
with the unequal eccentricity and consequent feathering action of Galloway.

The latest construction of the feathering paddle-wheel is seen in the
model of the engines of the " Princes se Henriette " (see No. 819).

958. Feathering paddle-wheel (working). (Diam. 18 in.)
Received 1861. N. 416.

This wheel was patented by William Tipple in 1861 ; it is one of the
numerous proposals made for securing a feathering motion of the floats by
weighting their lower edges.

The rings of the wheel are connected by horizontal axes on which the
floats can turn ; the axes are on the centre of each float, but balance weights
are added to maintain the floats in a nearly vertical position.

959. Feathering paddle-wheel (working). (Diam. 11 '5 in.)
Contributed by Messrs. Jackson and Watkins, 1860.

N. 414.

This construction closely represents that patented by Mr. H. C.
Daubeny in 1840 and subsequently by many others.

The floats are sector- shaped and are held between an external rim and
the centre of the wheel on radial spokes. The inner end of each float is
fitted with two sets of lugs, which act as teeth in turning the floats through
90 deg. twice in a revolution, as the lugs come into contact with projections
on a cam surface attached to the vessel.

960. Feathering paddle-wheel (working). (Diam. 14 in.)
Contributed by Richard Vines, Esq., 1861. N. 760.

This arrangement was patented by Mr. Tines in 1860 as a means by
which the floats should be so turned as to pass edgeways through the
air, but present their full faces while immersed. The floats turn on radial
spokes, but not round a central line, and are so weighted that on leaving
the water they swing round and turn into the plane of the wheel. This
weighting causes them to turn again when entering, and the position of the
axis, together with a stop, ensures that the floats remain full- face while
acting on the water.



323

961. Paddle-wheel with revolving floats (working). (Diam,
11 ' 5 in.) Contributed by William Smith, Esq., 1870.

N. 1321.

This feathering arrangement, patented by Mr. John Dean in 1861, has
been described as a compound paddle-wheel. A similar idea had been
patented in 1827 by Mr. Paul Steenstrup.

On the circumference of the wheel are six cylindrical frames that are
practically small radial-float paddle-wheels. On the axis of each small
wheel is a pinion of 15 teeth gearing into a spur ring of 120 teeth fixed to
the vessel's side, so that each frame makes seven revolutions for every one
of the wheel, and its floats describe trochoidal loops. The small wheels
were to dip into the water up to one-third of their diameter.



SCREW PROPELLERS.

Although the Archimedean screw is at least 2,000 years old,
its application to navigation is a comparatively recent invention.
In 1752 Daniel Bernouilli described a plan for a boat propelled
by wheels with vanes inclined at an angle of 60 deg. ; these
wheels were, however, to be placed at the sides, bow, and stern,
and to be driven by bevel and spur gear. Bramah, in his patent
of 1785, proposes a similar wheel, and as both windmills and
smoke-jacks were then quite common, it is not surprising that
many others saw the possibility of such an arrangement being
converted into a propeller. The blades of these early proposals
were not true helices, however ; but when the correct principle
was recognised, screws of at least two complete turns were
thought necessary, and in this form they were at first generally
constructed. As regards the position for the screw, there is
scarcely any place round the vessel that has not been proposed,
but Lyttleton, in 1794, placed it in an opening in the deadwood
aft, where it has since been most generally accommodated.

The first experimental screw steamer appears to have been a
launch tried on the river Hudson in 1804 by Col. J. C. Stevens,
of Hoboken, N. J. It had a cylinder 4 ' 5 in. diam. by 9 in.
stroke, and a boiler of 1 in. diam. copper tubes. There were
two propellers driven by gearing from the engine, and the speed
attained was 3 ' 5 knots.

To Sir F. P. Smith as patentee, Henry Wimshurst as ship-
builder, and the Ship Propeller Co. as financiers, must be given
the credit of bringing the screw into practical use when in 1838
they built and exhibited all round the coast of Great Britain the
S.S. "Archimedes." Smith's original screw had one complete
turn of a single thread, but it was quickly, though accidentally,
found that less would do and that a quarter of a turn with two or
three threads was all that was necessary with a properly designed
afterbody. To the general neglect of the influence of the afterbody
must be attributed the great amount of " slip " and the conflicting
results obtained from the different early screws subsequently
introduced.

When the screw was established the number of the propellers
proposed was enormous, even birds and beasts being drawn

x 2



324

upon to serve as models ; but the only early modification which
achieved general success was that of Robert Griffiths, which is
still extensively adopted for all services.

As the application of the screw propeller extended, a serious
practical difficulty arose in large vessels through the rapid
wearing of the outer bearing of the shaft. Numerous special
alloys were tried, but with little success, and it is stated that in
the "Malacca," a ship of 1,700 tons, this bearing wore away
at the rate of 5 ' 2 Ib. per day. In 1854, however, John Penn
invented the lignum vitee bearing which has since been univer-
sally adopted ; it was first tried on the " Malacca " with the
result that after she had steamed 15,000 miles the wear was
only '03 in. In addition to the slight friction and wear of
this arrangement, it has the merit of requiring no lubrication
beyond that given by the surrounding sea-water.

As engine power was at first generally auxiliary, some means
of obviating the resistance of the screw when under sail alone
was generally required. The two methods were, by raising the
screw above the water-level, or by turning its blades till they
offered their least resistance. In both methods the two-bladed
screw was usually employed ; in the former it was lifted from
its normal position up into a well reaching to the deck, while in
the latter it was turned vertically and then had its blades set till
they were nearly flush with the deadwood. Lifting the screw
is now almost abandoned, but arrangements for readily altering
the pitch or inclination of the blades are frequently fitted on
steam yachts in which the best total result can only be obtained
with a pitch that is suited to the sailing power of the wind.

The first twin screws driven by separate engines were fitted
in 1840 by Capt. E. J. Carpenter, R.N., but the arrangement did
not come into extensive use till the increased power of marine
engines rendered subdivision more desirable. In 1866 they were
first adopted in the Royal Navy, being tried in some of the
smaller vessels, and after 10 years' experience were generally
fitted in all classes of warships ; their use in the mercantile
marine dates from about 1881, when the first twin-screw liner
crossed the Atlantic.

With the introduction of the steam turbine into vessels, and
the higher power developed in modern ships, a further sub-
division of power has become necessary. The Hon. C. A. Parsons,
on the "Turbinia" in 1894, employed nine screws on three
shafts, but tandem screws have since been abandoned for turbine-
driven vessels, as the turbine is now designed to move sufficiently
slowly for the power to be transmitted by a single screw on
each shaft.

The phenomenon known as cavitation, first investigated by
Mr. S. Barnaby, i.e., the formation of air spaces in the water
being acted upon by the screw, generally produced by high
speed, or too small blade surface for the power transmitted,,
assumed great importance when the steam turbine appeared,
and it became necessary to construct propellers of comparatively



325

small diameter and blades of increased width. At the present
time the practice on turbine vessels is to subdivide the power
amongst three or four screws on separate shafts.

The modern screw usually has three or four blades, shaped
after the Griffiths pattern, the blades being usually cast with a
flange by which they are bolted to the hollow boss secured on
the propeller shaft. The materials used have comprised wrought
iron, cast iron, cast steel, and various bronzes, the last being now
most generally employed.



EARLY SCREW PROPELLERS.

962. Models showing the forms of screw propeller surfaces.
Woodcroft Bequest, 1903. N. 32-3.

A is a plain disc. If a section of this (as shown by the white paper) be
taken and placed at an angle to the axis the ineffective inclined plane
propeller is obtained (see No. 1000).

B is a screw of uniform and large pitch. A portion cut from this (as
shown by the white paper) gives the ordinary type of screw propeller.

C is a screw of increasing pitch, i.e., the angle of inclination of the
thread to the axis continually decreases. A portion cut off as before gives
the type patented by Mr. Bennet Woodcroft in 1832. The second model
shows this still more clearly.

The advantage of increasing pitch is that the greater pitch of the after
part of the helix compensates for the backward motion given to the water
already acted on by the fore part. Had a complete turn of the thread been
necessary, this would undoubtedly have been of importance, but with the
short length now found to be more suitable it is a refinement of little value.
Experiments were made in 1841 in the " Archimedes " with this increasing
pitch, when it was found that the same speed was obtained as with a
uniform pitch with 5 5 per cent, less engine power ; in 1844 a similar test
by the Admiralty showed a saving in power of 6*5 per cent., but these
screws were much longer than those now used.

963. Single and double helices. Contributed by Messrs.
Jackson and Watkins, 1861. N. 422.

These models have thin-bladed brass screws working in a sectional metal
nut of considerable length. One screw is single of two turns 3 in. pitch ;
the other screw is double of four turns 1 5 in. pitch. Short sections of these
threads would represent forms of propellers that have been used.

964. Stern model with Bramah's propeller. Contributed by
Messrs. Jackson and Watkins, 1861. N. 425.

This was made from the description contained in a patent taken out by
Joseph Bramah in 1785. A paddle vessel with a stern wheel of 16 floats is
there illustrated ; but instead of this " may be introduced a wheel with
" inclined fans or wings similar to the fly of a smoke- jack or the vertical
" sails of a windmill," this may be fixed in or beyond the stern and " may
be wholly under water."

965. Stern model with Lyttleton's propeller. (Scale 1 : 24.)
Contributed by Messrs. Jackson and Watkins, 1861.

N. 426.

This was made from the patent drawings deposited in 1794 by Mr.
William Lyttleton, a merchant of London.



326

The screw is triple-threaded and of a length equal to one complete turn ;
35 deg. is the angle recommended for the thread, and the number of threads
or " sweeps " is to be in proportion to the diameter. The screw is supported
in a frame hung either beneath the stern outside the rudder, at the bow, or at
the sides. It is turned by men working at a winch connected by ropes and
pulleys to the screw shaft ; but " it may be done far more effectually by
" means of a small steam engine."

966. Stern model with Snorter's propeller. (Scale 1 : 16.)
Contributed by Messrs. Jackson and Watkins, 1861. N. 427.

This shows the " perpetual sculling machine " included among other
propelling devices in the 1800 patent of Edward Shorter, a mechanic of
Newington, Surrey. It was made from his patent drawings which show a
screw of " two blades or more, similar to the sails of a windmill and set in
the same angular direction." The screw is entirely submerged in the
vessel's wake, but supported by a buoy to prevent it sinking too deeply.
The screw is driven by shafting and universal joints from a capstan, but
" a steam or vapour engine may be substituted." Two " guye ropes " from
the shaft to each side of the stern " have the effect of a rudder."

The arrangement was successfully employed in 1802 to propel H.M.
transport vessel " Doncaster " in Gibraltar Bay and again in Malta Har-
bour ; the speed attained was 1 5 miles per hour with eight men at the
capstan (see attached facsimile of certificate).

967. Pencil sketch of proposed propellers. Woodcroft Be-
quest, 1903. N. 92.

This sketch was made by Alexander Nasymth in 1819 to explain his
proposed " method of propelling vessels on water by steam power or
otherwise."

A screw of five turns is arranged in the deadwood aft, as shown in
Lyttleton's patent of 1794 (see No. 965). Another propeller is shown,
in which a number of inclined blades are secured to the shaft and to an
enclosing drum, after the manner of a smoke- jack.

968. Whole model of the " Sarah " of Lewes. (Probable scale
1 : 16.) Lent by Arthur Godlee, Esq., 1872. N. 1334.

This represents a double-hulled boat or raft, fitted with a screw, which
is placed in the midwater forward and driven, through a universal joint
and a long shaft, by manual power on deck. The screw is double-threaded,
with about three-quarters of a turn of each thread ; the central portion
is open.

The actual boat is said to have been tried on the Sussex Ouse in 1823,
but to have been decidedly slow.

969. Stern model with screw propeller. (Scale 1 : 32.) Wood-
croft Bequest, 1903. N. 42.

This framed model was made to the drawings deposited in 1828 by
Mr. C. Cummerow, with his application for a patent for a communicated
invention.

There is some evidence that the inventor was Jacob Ressel, of Bohemia,
who in 1827 is reported to have constructed at Trieste a screw-propelled
boat, 62 2 ft. long, 11 4 ft. beam, and 6 2 ft. draught giving about 80 tons
displacement. The screw was 5 2 ft. diam. and 5 2 ft. pitch, the engine
of 6 h.p., and the speed from 3 to 6 knots. In his French patent he says
that for an 80-ton boat the screw should be 6 ft. diam., 9 ft. long, and be
driven by an engine of 10 h.p. ; this he estimated to give a speed of 16 5
knots at 180 revs, per min. In a boat of 200 tons the h.p. was to be 30.

From Cummerow's vague specification it appears that the screw was to
have a single whole turn, and that it might be arranged in the deadwood



327

aft, or at the bow, or in the middle space of a double-hulled boat ; the steam
engine was to drive the " spiral " at 150 revs, per min. by means of gearing.

An adjacent block model (scale 1 : 24), contributed by Messrs. Jackson
and Watkins, gives another representation of this scheme (N. 428).

970. Whole block model of S.S. "Francis Smith." (Scale
1 : 12.) Wooclcroft Bequest, 1903. N. 43-44.

This represents a launch built in 1836 at Wapping, in accordance with
the patent of Sir F. P. Smith, and successfully tried on the Paddington
Canal in the following year. At the time the patent was granted Mr. Smith
was a farmer at Hendon, in Middlesex, and had constructed a clockwork-
driven model of a screw ship which propelled itself successfully on a pond
at the farm. This was followed by the boat represented, which was the
first practical experiment ; the boat was of 6 tons burden, and was driven
by a steam engine with a cylinder 6 in. diain. by 15 in. stroke. The pro-
peller was of wood, and in one of the trips about one half of it was broken
off ; it was then noticed with much surprise that the accident had materially
increased the speed of the boat.

The screw was as described in the patent, and had two complete turns,
as seen in the model. It was located aft, but some distance in front of the
stern post, and was driven by bevel gearing through a vertical shaft that
by other bevel wheels was connected with the engine. From the informa-
tion derived from this boat, Mr. Smith amended his specification, and
described his screw as one having a single turn only, or two half-turns.
The boat was subsequently fitted with a metal screw of the improved form,
and then made some short trips, as from London to Folkestone, at a speed
of about 5 5 knots.

From the model, the boat appears to have had a clean run aft, and to
have been of the following dimensions : Length (b.p.), 29 ft. ; breadth,
5 75 ft. ; draught, 4 ft. ; screw, 2 ft. diam.

971. Models of the stern framing of S.S. "Archimedes."
(Scales 1 : 24 and 1 : 32.) Lent by Henry Wimshurst, Esq.,
1873. N. 1342-4.

From the successful results obtained with the " Francis Smith " (see
No. 970), it was decided by several gentlemen to commercially test the
system of screw propulsion by forming a syndicate, which became the " Ship
Propeller Co.," and purchased Sir F. P. Smith's patents. Mr. Wimshurst,
who was one of the members, was instructed to build the " Archimedes " ;
she was launched in November, 1838, and was of the following dimensions :
burden, 240 tons; length (o.a.), 125 ft.; length (b.p.), 106*7 ft.; breadth
(extreme), 22 -5 ft, ; depth of hold, 13 ft. ; draught forward, 9 ft. ; draught
aft, 10 ft. ; immersed midship section, 140 sq. ft.

The engines, constructed by Messrs. J. and G. Rennie, had two cylinders,
37 in. diam. by 36 in. stroke, made 26 revs, per min., and were supplied
with steam at a pressure of 6 Ib. per sq. in. They drove the propeller shaft
through gearing in the ratio of 3 : 16, so that the screw made 140 revs,
per min.

The propeller shown was that first tried, and was 7 ft. diam., 8 ft. pitch,
and 8 ft. long, the helix making one complete turn. The two detached
models sjiow modifications subsequently tried, in which double- threaded
screws are employed and the length reduced ; the propeller finally adopted
was 5*75 ft. diam., 10 ft. pitch, and two-bladed, as described in Smith's
amended patent.

On the wall are two aquatints, representing the "Archimedes." (See
No. 972.)

972. Aquatints of S.S "Archimedes." Presented by Vice-Adm.
E. P. Halsted, R.N., 1866. N. 1296.

These represent this pioneer screw vessel on her voyage from London to
Portsmouth in 1839, which she accomplished at a speed of 8 knots against
wind and tide.



328

She afterwards went round the British Isles, and did some over-sea
voyages. (See No. 971.)

973. Testimonial plate. Bequeathed by Sir Francis Pettit
Smith, 1871. N. 1332.

This silver jug and silver vase were presented to Sir F. P. Smith in 1858,
as a recognition of his labours in introducing screw propulsion. Upon
them is engraved a view of the S.S. " Archimedes." The accompanying
address gives the names of the screw ships in the Royal Navy in 1858,
together with other particulars, and also contains some interesting
signatures.

974. Whole block model of S.S. "Novelty." (Scale 1 : 24.)
Lent by Henry Wimshurst, Esq., 1878. N. 1504.

This represents a screw steamer built at Blackwall in 1839 by Mr.
Wimshurst, to further test the merits of screw propulsion. It was a
considerably larger steamer than the " Archimedes " (see No. 971), and was a
great improvement on the earlier vessel in having the propeller as close to
the stern post as possible, and in the form of the propeller, which had only
two blades, each making a quarter of a turn. The " Novelty " was the first
screw cargo steamer ; her first commercial voyage was from Liverpool to
Constantinople, when she took 420 tons of cargo, besides coal, and returned
to London with a cargo of fruit, without any trouble occurring.

The engines had two cylinders 14' 5 in. diam., that drove the propeller
shaft directly ; they were supplied with steam at 60 Ib. pressure, but owing
to the objections raised, new engines working at a pressure of 15 Ib. only
were subsequently substituted. The ship was barque-rigged, but the mizen-
mast was built of iron, 58 ft. long by 15 '5 in. diam., and was utilised as a
funnel. It was the first iron mast ever used.

Length, 117 ft. ; breadth, 24-5 ft. ; depth, 14 -5 ft.

975. Built model of stern of S.S. " Novelty." (Scale 1 : 24.)
Lent by Henry Wimshurst, Esq., 1878. N. 1343.

This shows in detail the construction of the afterbody and the position
of the screw ; in the whole model of the " Novelty " (see No. 974) the
proportions of the screw differ considerably from those here indicated. The
vessel was provided with two wells and an arrangement of davits, by which,
after the propeller had been slightly raised it could be lifted on deck, over
the ship's side, so as to avoid its resistance when under sail only.

976. Stern model with Ericsson's propeller. (Scale 1 : 24.)
Contributed by Messrs. Jackson and Watkins, 1861.

N. 429.

This propeller was patented in 1836 by John Ericsson, the celebrated
Swedish engineer. It consists of two drums, from the exteriors of which
project seven helical blades strengthed by an external hoop ; the interior of
each drum contains the boss and three blades which act also as arms. The
drums are arranged behind the rudder on a common axis ; the f orward drum
is secured to a tubular shaft through which passes the shaft of the after
drum. The blades of the two drums are of opposite inclination, and the
drums revolve in opposite directions ; the forward drum rotates at 1 2 times
the speed of the other. The object of this duplex arrangement is to avoid
loss due to the rotary motion left in the water discharged from a single
screw ; later experience has shown that the energy so lost is unimportant
and not worth the extra complications that its recovery necessitates ; the
fact that tandem screws are used in the Whitehead torpedo is due to the
amount of ballast that would otherwise be necessary to prevent the torpedo
itself rotating.



Online LibraryScience Museum (Great Britain)Catalogue of the naval and marine engineering collection in the ... museum .. → online text (page 46 of 58)