The Trebuchet
a History
from The Crossbow
by Sir Ralph Payne-Gallwey 1903
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 |
This engine was of much more recent invention than either
the catapult or the ballista 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 ballista 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trebuchet in great measure superseded the catapult.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 |
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.
|
| 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.
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.
|
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., |
Fig.
214 - Front
and Side View |
| 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.
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.
|
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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