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The model here shown is representative of four twin-screw steel hopper-
barges, built and engined at Paisley in 1892-3 by Messrs. Fleming and
Ferguson for the Clyde Navigation Trustees.

The large single hold or hopper is placed amidships and is framed
internally, at the lower part, to carry twelve hinged doors opening down-
wards, for discharging the spoil. A strong arched middle-line girder
connects the upper ends of the hopper and carries the fair-leads for the
lift-chains to the hopper doors. For working these doors there are special
steam windlasses, fitted with separate winding drums for each pair of
doors.

For propulsion, two sets of three- stage expression engines are used
with cylinders 15 in., 24 in., 37 in. diam., and 24 in. stroke ; a speed of 10*5
knots is attained with 1,200 indicated h.p.

Gross register, 799 tons ; length, overall, 200 ft. ; breadth, 35 ft. j.
depth, 15 '5 ft. ; hopper capacity, 1,250 tons.

1128. Whole model of rockcutter. (Scale 1 : 48.) Lent by
Messrs. Lobnitz & Co., Ltd., 1906. N. 2390.

Before removing sub-aqueous rock by dredging, some form of machinery
is necessary to crush it to a suitable size. This shows a rockcutter patented
in 1886 by Mr. H. C. Lobnitz and since improved by Mr. F. Lobnitz ;
it is, in this case, mounted on a steel pontoon, but is more usually mounted
on two barges joined together by logs of wood or steel girders bolted
across above their decks. In the present example, the pontoon has a
central well provided with upright side timbers and struts, within which
is a guide formed by a frame of cross beams. The guide has steel wearing-
plates and can be raised by the hoisting rope to any height suitable to
the depth of water in which the cutters are operating. Between the guide
and the upright timbers are placed springs forming cushions to take any
shock caused by the cutters striking an inclined face of the rock. The
cutters fall freely through steel-lined holes in the guide.

The machine shown is a double one, having two steel cutters, each
weighing 13 tons, fitted with renewable points whose hardness increases
from the point to the inside. These cutters are graduated in feet and
inches painted on their surface and are attached at the top to a wire rope of
about 5 in. circumference, working over a pulley at the top of sheer legs
fastened to the pontoon. The rope is operated by a hoisting winch, and the
cutters are allowed to fall by their own weight on the surface of the rock,
breaking it and partly pulverising it. The winch then hoists the cutters for
another blow on the same spot until the desired depth of rock is
broken up.

The hoisting winch is a powerful steam engine capable of giving about
2,000 blows per day of ten hours. The winch has a steel friction clutch
which releases the barrel on which the hoisting rope is wound when the
cutter is falling (the barrel then revolving independently of the driving
shaft of the winch) but, immediately the tension on the rope is released as
the cutter strikes the rock, the barrel engages with the driving shaft of the
winch, thus raising the cutter for the next blow. In the early machines



380



the levers for working the clutch were operated by hand, but in 1902 patent
automatic gear was introduced to perform this operation. This gear consists
essentially of a heavy weight operating a bell-crank lever, which tightens
the coil clutch upon the shaft of the winch when the cutter strikes the
rock. To operate the weight, advantage is taken of the fact that the rope
slackens when the cutter strikes ; a pulley resting on the rope is then
released and the lever attached to it operates the weight.

The method of accurately manoeuvring the pontoon to strike successive
spots at the desired intervals of about 2 ft. is important. On the pontoon
are set up two vertical rods, mounted in slots in a frame, which can be
moved into other slots at intervals corresponding to fresh positions for the
cutter. A base line is established on shore and square to it are set up two
rods which are sighted in line with the rods on the pontoon and thus form
sighting points. Moving the pontoon is performed by six manoeuvring
chains worked by a special steam winch upon which are six independent
barrels ; the four side chains are used to traverse the work, and the two
remaining chains move the pontoon in a fore-and-aft direction. The winch
is so arranged that the amount of chain taken in on the one side is equal
to the amount given out on the other. Very accurate results can be obtained
in this way. The rock having been broken up can then be dredged by an
ordinary dredger, the bucket type being the most suitable.

The dimensions of the pontoon are: Length, 100 ft.; breadth, 36 ft. ;
depth, 8 ft. The rockcutter shown is suitable for cutting to a depth
of 40 ft.

1129. Suction dredger " Leviathan." (Scale 1 : 48.) Lent
by Messrs. Cammell, Laird & Co., Ltd., 1910. N. 2555.

This represents an unusually large example of a self-propelled sand-
pump dredger specially designed for deepening the sea approaches to the
port of Liverpool. It is of the twin screw, hopper type and was built of
steel by Messrs. Cammell, Laird and Co. at Birkenhead in 1908 for the
Mersey Docks and Harbour Board.

The main structure is subdivided by eight transverse watertight bulk-
heads extending to the upper deck, and also by a continuous longitudinal
bulkhead extending from the after end of the boiler room to the fore side of
the buoyancy space in front of the hopper. The hopper space itself is
162 ft. long and 49 ft. wide subdivided into twelve compartments ; structural
strength in the way of these open areas is maintained by fore-and-aft deck
girders and diagonal tie-bars ; a deep steel coaming surrounds the hopper,
and the buoyancy spaces on each side are 10 ft. wide.

Four suction tubes are used, of sufficient length to raise sand from a
channel 70 ft. in depth : these are built up of steel plates, with cast steel
flanges for connection with the swivel joints and nozzle ; they are arranged
to turn freely about a vertical or a horizontal axis and each tube is raised
and lowered by two derricks worked by a single steam winch. Four
G-wynne centrifugal pumps are used for lifting the spoil and delivering
it into the two large rectangular ducts or " landers " which extend the
full length of the hopper. This mixture of sand and water usually falls
into the foremost hopper divisions at first and then overflows into adjacent
divisions ; the sand thus gradually settles to the bottom while the surface
water is drained off by means of two weirs placed at the after end of the
hopper.

The " dumping " or discharging of the sand is effected by large hydraulic
valves or cylinders extending from the bottom of the hopper to the deck
level and working at a pressure of 800 Ib. per sq. in.

A full load of 10,000 tons can be raised in 50 mins. and discharged in
10 mins.

Two sets of three- stage expansion engines were fitted for propelling
purposes by Messrs. D. Rowan and Co., Glasgow; they have cylinders
22-5 in., 37 in., 61 in. diarn., and a stroke of 45 in. Steam is supplied at



381

180 Ib. pressure by four boilers each 16 ft. diam. and 11 * 75 ft. long. On
steaming trials an average speed of about 10 5 knots was realised.

The principal dimensions of the vessel are : Length, between perps.,
465 75 ft, ; breadth, moulded, 69 ft. ; depth, 30 6 ft.



AERIAL NAVIGATION.

A body may be supported in the air by flotation, as in
ballooning, or gravitation may be resisted by the expenditure of
mechanical energy in giving sufficient downward momentum to
some of the surrounding air, as in flying. An important
modification of the latter method is seen when a bird soars, an
action in which it probably utilises the energy in air currents,
although the cause of soaring flight is even now but little
understood.

The introduction of the free balloon is generally attributed
to the brothers Montgolfier who, in 1783, used a spherical
balloon filled with, heated air. Professor Charles of Paris, and
others, in the same year substituted hydrogen gas as the lifting
agent, and by this gas the first human ascent was made. At
the present time hydrogen, or its cheaper compounds, is exclu-
sively used for the inflation of balloons, although the violently
explosive character of hydrogen when mixed with air in suitable
proportions is a source of great danger. Its use has been greatly
facilitated by the practice of compressing the gas into easily
transportable steel cylinders.

The difficulty of guiding a free balloon has prevented the
invention becoming of any great practical utility, although such
balloons have been successfully employed in several wars, e.g.,
during the siege of Paris in 1871. As not less than 13 ' 4 cub. ft.
of hydrogen, the lightest known gas, are required to give a
lifting power of 1 Ib., the size of a balloon causes the air to
offer to its motion a considerable resistance, which can only
be overcome by a corresponding expenditure of energy. As,
however, the lifting power of a balloon increases with its
dimensions at a greater rate than does the resistance of the air,
and as the resistance can also be considerably reduced by
adopting an elongated form, large dirigible balloons propelled by
mechanical power have been produced. One of the earliest
successful dirigibles was that of Henri Giffard, a Frenchman,
who, in 1852, invented a spindle-shaped gas-bag, propelled by
a 3 h.p. steam engine. Commandant Renard, of the French
Army, in 1884-5 designed the dirigible balloon " La France," in
which he employed an interior balloon called a ballonet,
which, when filled with air, kept the outer or main gas-bag
taut, power being provided by a Gramme electric motor
developing 9 h.p. In 1901 A. Santos-Dumont commenced
the construction of a series of successful dirigibles, with one of
which he rounded the Eiffel tower, occupying 30 min. in going



382

a distance of 9 miles. Until this period all dirigible balloons
had been of the semi-rigid or non-rigid types. In the former
the balloon is connected with the car by a trussed frame of steel
or aluminium tubing, while in the latter the car is suspended
from the balloon by suspension wires. In order to reduce the
head resistance, Count Zeppelin, who began experimenting in
1898, greatly increased the length of the balloon in proportion
to its diameter, and as the semi-rigid method of staying was
obviously unsuited to balloons of great length, he employed a
rigid framework of aluminium, strengthened by aluminium
partitions which divided the balloon into 17 separate compart-
ments. The whole framework was covered with rubbered
fabric and each compartment contained a hydrogen balloon
furnished with a separate automatic valve. Each of the two
cars, suspended from the framework by tubes, contained a petrol
motor, actuating two three-bladed propellers, the whole being
-constructed of aluminium. Zeppelin No. VII., which was
completed in 1910, and in the same year wrecked in a storm
while conveying passengers on a pleasure trip, had a capacity
of 19,000 cub. metres, and could exert 340 h.p.

The term "aviation" is usually confined to systems of
mechanical propulsion independent of buoyancy. There are
three distinct types of flying-machines in this class :

(a) Ornithopters, i.e., those which depend upon the reci-
procating action of wings, after the manner of birds. This
type of machine dates back to the earliest times, but it has
been almost uniformly unsuccessful.

(6) Helicopters, i.e., those in which a direct vertical lift is
provided for by propellers rotating on a vertical axis. This
principle can be traced to Leonardo da Vinci about 1500 A.D.
Notwithstanding the fact that this type of machine has been
experimented with, a very limited amount of success has been
attained up to the present.

(c) Aeroplanes, i.e., those having inclined surfaces which
when propelled horizontally deflect the air traversed, and so
experience an upward pressure dependent upon the speed.

The attempts to solve the problem of aerial navigation by
means of aeroplanes date back to the year 1842, when W. S.
Hensoii and J. Stringfellow constructed a model (see No. 1130),
which, although unsuccessful, bears a striking resemblance to
the monoplane of to-day. Stringfellow, in 1846, designed a
model which actually performed a free flight (see No. 1132).
Subsequently Otto Lilienthal, of Berlin, with the assistance of
his brother Gustave, thoroughly investigated bird flight, and,
in 1889 and the following years he investigated the conditions
of the maintenance of equilibrium in flight.

Professor Langley, of the Smithsonian Institution, after
many experiments, constructed, in 1896, a double monoplane
model, which flew over the Potomac river. Sir H. Maxim, in his
famous experiment in 1894, employed large supporting sur-
faces which were propelled horizontally by twin-screws driven



383

by a powerful steam engine (see Nos. 1133-4). He found that
1 h.p. expended upon the air propellers give a lifting effort of
130 lb., while his motor arrangements weighed but 13 Ib. per
indicated h.p. The first experimenters to achieve successful
flight in a power machine were Messrs. Wilbur and Orville
Wright of Dayton, Ohio, U.S.A. (see No. 1137). Profiting by
the valuable researches of Lilienthal, the brothers Wright
succeeded, in 1903. after much preliminary gliding, in making
a free flight with power in a biplane. Subsequently they
patented in America the method of securing lateral stability
by warping the wing tips. In France the brothers Voisin
designed the box-kite type of biplane with which excellent
flights were made in 1907-8. Mr. Henri Farman modified this
form, and designed a biplane which has been very successful.
He used hinged flaps or ailerons, on the rear corners of his
main planes, to secure lateral stability, in place of the warping
mechanism of the brothers Wright. Mons. L. Bleriot developed
the monoplane by constructing a series of successful machines
(see No. 1136), while M. Santos Dumont with his famous
" Demoiselles " (see No. 1135) made great advances with regard
to cheapness, lightness, and speed.

The only machine which has a special starting device is the
Wright ; all others start by running along the ground on wheels
until the necessary speed for lifting has been attained.

The triplane has been experimented with, but so far as has
been at present ascertained no advantage results from increasing
the number of superposed surfaces.

The rapid development of aeroplanes in the last few years
has been due in a great measure to the reduction in weight
of the motor owing to the adoption of the internal combustion
engine. Since 1903, the attention of engineers has also been
directed to the construction of light-weight motors capable of
running for a long continued period without attention.

1130. Model of proposed flying machine. (Scale 1 : 7.)
Presented by P. Y. Alexander, Esq. and C. H. M. A.
Alderson, Esq., 1907. Plate XII, No. 5. N. 2430.

This model, the design for which was patented in 1842 by Mr. W. S.
Henson, was built in 1844-5 by Messrs. Hensoii and J. Striiigfellow.
Henson's proposal to utilise the fixed surfaces of an aeroplane to obtain
support from the air was regarded at the time as a possible solution of the
problem of flying. Henson' s idea was to imitate soaring birds, all previous
attempts being based on vibrating or rotating surfaces, after the manner of
flapping birds. It was intended that the actual machine should be used as
a conveyor of letters, goods, and passengers.

The model consists of an extended surface or aeroplane of oiled silk or
canvas stretched upon a bamboo frame made rigid by trussing, both above
and below. A car is attached to the under side of the aeroplane to contain
the steam engine, passengers, etc. It has three wheels to run freely upon
when it reaches earth. Two propellers 3 ft. diam. are shown with their
blades set at 45 deg. ; they are operated by endless cords from the steam
engine (see No. 1131). Behind these is a fan-shaped tail stretched upon a
triangular frame capable of being opened out, closed, or moved up and down
by means of cords and pulleys. By this latter arrangement ascent or



384

descent was to be accomplished. A rudder for steering sideways is placed
under the tail, and above the main aeroplane a sail (not shown) was to be
stretched between two masts rising from the car to assist in maintaining
the course. When in motion the front edge of the plane was to be raised
in order to obtain the required air support. To start the model it was
proposed to allow it to run down an incline, e.g., the side of a hill, the
propellers being first set in motion. The velocity gained in the descent was
expected to sustain it in its further progress, the engine overcoming the
head resistance when in full flight. Experiments were eventually made on
the downs, near Chard, and the night trials were abandoned, as the silk
became saturated from a deposit of dew. After many day trials, down wide
inclined rails, the model was found to be deficient in stable equilibrium for
open air experiments, little puffs of wind or ground currents being sufficient
to destroy the balance. The actual machine was never constructed, but in
1847-8 J. Stringfellow built a model which is supposed to be the first flying
machine which performed a successful flight (see No. 1132).

The dimensions of the model shown are 20 ft. from tip to tip of wings,
by 3 ' 5 ft. wide, giving 70 sq. ft. sustaining surface to the wings and about
10 sq. ft. in the tail. Its weight is about 25 Ib. The actual machine was
to weigh about 3,000 Ib., with 4,500 sq. ft. surface in the wings, and 1,500
sq. ft. in the tail. A lithograph of the proposed machine is shown.

1131. Engine for Henson-Stringfellow flying machine model.
Presented by C. H. M. A. Alderson, Esq., 1907. N. 2429.

This steam engine was constructed to provide power for propelling the
model shown suspended from the ceiling (see No. 1130). It was placed
inside the car, at the after end, in a vertical position, and was connected
with the propellers on the flying machine by endless cords running over the
wooden pulleys shown. The engine is direct-acting and has a single
cylinder 1'5 in. diam., by 3 in. stroke. On the crank-shaft is fixed the
grooved pulley for driving the propellers. The framework consists of an
angle-iron structure containing the bearings for the crank-shaft and
supporting the cylinder.

The boiler consisted of 50 inverted truncated cones arranged around
and above the furnace, and connected with a steam drum ; they presented
100 sq. ft. of heating surface. The air-cooled tubular condenser gave a
vacuum of from 5 to 8 Ib. The speed of this model engine was to be
300 revs, per min., and the actual engine was intended to develop 25 to
30 h.p.

1132. Portions of Stringfellow's flying machine model of
1846-8. Presented by Sir J. H. Heathcoat-Amory, Bart.,
P. Y. Alexander, Esq., and C. H. M. A. Alderson, Esq.,
1909. N. 2467.

The model, of which the wings, tail, engine and boiler are shown, was
constructed by Mr. J. Stringfellow in 1846 and was designed for indoor
experiments. The sustaining planes were shaped liked the wings of a bird
and were slightly curved on the underside. They were also feathered at
the back edge, in order that the yielding of the feathers might automatically
regulate the fore and aft stability. It is stated that during the experiments
the model rose after leaving the sustaining wire as much as 1 in 7, and
a free flight of about 40 yds. was eventually made with the model. The
sustaining surface was 17 sq. ft. and the planes measured 10 ft. over
the tips.

The motive power was supplied by a steam engine placed inside a car
between and underneath the wings. It had a cylinder 75 in. diam. by 2 in.
stroke. The boiler was of the water-tube type as used by Henson and
Stringfellow, and consisted of inverted truncated cones arranged around
and above the furnace and connected with a steam drum. The propeller
speed was increased in the ratio of 3 : 1 by bevel gear on the crank-shaft.
The two propellers were 16 in. diara. and were four-bladed.



385

The weight of the model, including the engine, was 6 Ib., and with
water and fuel 6 5 Ib.

The engine and boiler, which have since been used to work a small
lace machine, are not now in their correct relative position as used by
Stringfellow.

1133. Model of Maxim's flying machine. (Scale 1 : 12.)
Presented by Sir Hiram S. Maxim, 1907. N. 2092.

This is a complete model of the flying machine constructed and
experimentally tried by Sir Hiram Maxim in 1894 ; by its own effort it more
than supported its weight and that of its crew. It never soared aloft,
however, as its rise was limited by inverted rails to a few inches only, and
an accident when running under these at a speed of 40 miles per hour
brought the experiments to a premature conclusion. The total weight of
the machine was 7,700 Ib., and it exerted in the trials a total lifting effort
of 10,000 Ib.

The machine consists of a braced structure of steel tubes and wires
connected to large inclined surfaces, called aeroplanes, that possess a total
area of 5,400 sq. ft., and slope at an angle of 7*25 deg. with the horizontal.
The extreme width of the machine is 120 ft., and the length 104 ft.

1134. Engines and propeller for Maxim's flying machine.
Presented by Sir Hiram S. Maxim, 1907. N. 2092.

One of the two-stage expansion engines patented in 1889, and the two-
bladed propeller which it drove, on Sir Hiram Maxim's flying machine, are
shown. The engine weighs only 300 Ib. and exerts 180 h.p., or over 5 h.p.
for every pound of weight. The high-pressure cylinder is 5 05 in., and the
low pressure 8 in. diam., with a stroke of 12 in. Steam is distributed by
piston valves with a travel of 3 in. ; the high-pressure cut-off is at 75 of
the stroke, and the low pressure at '625. The speed of the engines is
375 revs, per min.

Steam at 300 Ib. pressure is supplied from a tubulous boiler of the
Thomycroft type, fired by naphtha delivered through hollow firebars as
7,650 spray jets under a pressure of 50 Ib. The boiler has a heating surface
of 800 sq. ft. and a grate area of 30 sq. ft. ; its weight is 900 Ib., and with
feed-heaters, burners, and water 1,200 Ib.

The propeller is 17*83 ft. diam., of the two-bladed type, 16 ft. pitch, and
5'16 ft. wide ; the two engines and propellers have driven the machine
along at the speed of 40 miles per hour, and obtained a horizontal thrust of
2,000 Ib. from the air passing them.

1135. Model of Santos-Dumont monoplane. (Scale 1 : 10.)
Made in the Museum, 1910. N. 2542.

As the lightest practical machine that has successfully flown, the
" Demoiselle " represented by the model is of considerable interest. With
it M. Santos-Dumont rose from the ground after travelling 230 ft. in the
record time of 6 2 sees, and attained the high speed of 60 miles per hour in
free flight.

The introduction of bamboo as the material for the main framework, the
wings and the tail, and the system of staying adopted have conduced to
make this type of machine exceedingly light and simple in construction.
The main frame is a girder of triangular section formed of three bamboos,
about 2-in. diam. at the larger ends, connected by steel struts of oval
section.

When stationary the machine rests on two bicycle wheels at the front
end and a skid near the rear ; these wheels are inclined in order to minimise
the stresses should the machine land sideways. At the forward end of the
chassis are the main planes or wings, the two chief supporting members of
which are transverse spars of ash, which taper slightly in depth, becoming
thinner where they join the central bamboo. Firm connections are made

B B



386

between the central bamboo and these spars by fitting them into rectangular
sockets brazed to bosses on the framework. The fabric which encloses the
spars and bamboo ribs is double, and is formed of silk. The leading and
trailing edges of the planes are quite sharp, and are supported by wires held
in claws at the ends of the bamboo ribs. TJie fabric envelops the wire at
the leading edge, but at the trailing edge it is laced to the wire, thus
ensuring that the wings are stretched tightly. The greatest camber of the
planes is slightly in front of the centre and is approximately 4 in.

The tail is built up of fabric stretched on a bamboo frame, and moves as
a whole about a universal joint formed at the after end of the chassis. The



Online LibraryScience Museum (Great Britain)Catalogue of the naval and marine engineering collection in the ... museum .. → online text (page 54 of 58)