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Fig. 211 - The Trebuchet
The arm is fully wound down and the tackle of the windlass is detached
from in. The stone is in the sling and the engine
is about to be discharged by pulling the slip-hook off the end of the arm.
N.B.- A Roman soldier is anachronistically shown in this picture.
The trebuchet was invented after the catapult
and the time of the Romans
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The Trebuchet
by Sir Ralph Payne-Gallwey 1903
This engine was of much more recent invention than either the catapult
or the balista of the Greeks and Romans.
It is said to have been introduced into siege operations by the French
in the twelfth century. On the other hand, the catapult
and the balista were in use before the Christian era. Egiclio Colonna gives
a fairly- accurate description of the trebuchet
and writes of it about 1280 as though it were the most effective siege
weapon of his time.
The projectile force of this weapon was obtained from the terrestrial
gravitation of a heavy weight, and not from twisted
cordage as in the catapult and
balista. |
| From about the middle of
the thirteenth century, the
trebuchet
in great measure superseded the catapult.
This preference for the
trebuchet was
due to the fact that it was able to cast stones of 300 lbs. and more in
weight or five or six times as heavy as those which the largest catapults
could project.
The stones of 50 to 60 lbs. thrown by siege
catapults would no doubt destroy towers and battlements, as the result
of the constant and concentrated bombardment of many engines. One huge
stone of 300 lbs., as slung from a trebuchet,
would however shake the strongest defensive masonry and easily break through
the upper parts of the walls of a fortress.
The trebuchet was essentially
an engine for destroying the defences of a fortification
, so that it might be entered by means of scaling ladders or in other ways.
From experiments with models of good size and from other sources I find
that the largest
trebuchets those with arms
of about 50 ft. in length and counterpoises of about 20,000 lbs. - were
capable of slinging a Stone 300 lbs. in weight
to a distance of 300 yards, a range of 350 yards being in my opinion more
than these engines were able to attain.
The trebuchet
made by order of
Napoleon III., and described in his ' Etudes sur l'artillerie,' had an
arm 33 ft. in length with a counterpoise of 10,000 lbs. weight to work
it. This machine projected a 50 lb. cannon-ball 200 yards, but was so lightly
constructed that its full power could not be safely applied. |
Fig. 212 - The Action
of The Trebuchet
A. The arm pulled down and secured by the slip-hook previous to unhooking
the rope of the windlass. B. The arm released from the slip-hook and casting
the stone out of its sling. C. The arm at the
end of its upward sweep.
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Fig. 213 - A Trebuchet with its Arm Being Wound
Down
Criticism.- Here we have a trebuchet with an arm
at least 60 ft. in length. An engine of such immense
sizes as this would require a score of men at its
windlass instead of a couple. The heavy stone was
placed in the great sling of thick netting
which
is suspended to the end of the arm.
The sling was identical in its action with
the
one given in fig. 212.
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In a book on ' Experimental Philosophy,' by J.T.
Desaguliers, 1734 a curious and interesting old work on mechanical effects,
the author gives a detailed calculation of the power of a trebuchet, together
with plans of the engine as constructed from the writings of Vitruvius.
These drawings are, however, inaccurate, and though Desaguliers' conclusions
are exact, he only allows the trebuchet a counterpoise of 2,000 lbs. which
would be far too light a weight to be of any service in an engine of the
kind.
The trebuchet is sometimes depicted in medieval
books with an arm like that of a catapult
(i.e. with a hollow in the end of the arm in which to rest the stone),
and without a sling , but this is incorrect.
The trebuchet always had a sling in which to
place its missile.
The sling doubled the power of the engine and
caused it to throw its projectile twice as far as it would have been able
to do without it.
It was the length of the arm, when suitably weighted with its counterpoise,
which combined with its sling gave power to the
trebuchet. Its arm, when released, swung round with a long easy sweep and
with nothing approaching the velocity of the much shorter arm of the catapult.
The weight of the projectile cast by a trebuchet was governed by the
weight of its counterpoise. Provided the engine was of sufficient strength
and could be manipulated, there was scarce a limit to its power. |
| Numerous references are to be found in medieval
authors to the practice of throwing dead horses into a besieged town with
a view to causing a pestilence therein, and there can be no doubt that
trebuchets were employed for this purpose. As a small horse weighs about
10 cwt., we can form some idea of the size of the rocks and balls of stone
that trebuchets were capable of slinging.
When we consider that a trebuchet
was
able to throw a horse over the walls of a town we credit credit the statement
of Stella who writes ‘that the Genoese armament sent against Cyprus in
1373 had among other great engines one which cast stones of 12 cwt.’
Villard de Honnecourt describes a trebuchet
that had a counterpoise of sand the frame of which was 12 ft. long, 8 ft.
broad, and 2 ft. deep. That such machines were of vast size will readily
he understood.
Leonardo da Vinci described a trebuchet
for defense of a fortification and a study of sling
release in his notebooks. |
Fig. 214 -
Front and Side View |
Fig. 215 - Trebuchets Throwing Barrels Filled With Earth Into
The Ditch Outside A Fortress So As To Enable The Besiegers To Pass
Over It And Apply Their Scaling Ladders To The Walls.
Criticism - A very elaborate and fanciful drawing. The counterpoise
of the nearer engine could not swing back between the uprights, and it
and the other engine would each require at least six men to work the windlasses.
The barrels would not be projected 30 yards and the men working the
engines would be slain by the archers on the battlements of the besieged
fortress.
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For instance, twenty-four engines taken by Louis
IX at the evacuation of Damietta ill 1249, afforded timber for stockading
his entire camp ;3 a trebuchet used
at the capture of Acre by the Infidels in 1291, formed a load for an hundred
carts ; 4 a great engine that cumbered the tower of St. Paul at Orleans
and which was dismantled previous to the celebrated defence of the town
against the English in 1428-9, furnished twenty six cart loads of timber)
All kinds of articles besides horses, men, stones and bombs were at
times thrown from trebuchets. Vassaf records
'that when the garrison of Delhi refused to open the gates to Ala'uddin
Khilji in 1296, he loaded his mangonels with bags of gold and shot them
into the fortress, a measure which put an end to the opposition.'
Figs 211, 212 & 214, explain the construction and working of the trebuchet.
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