Projectile Throwing Engines
Sir Ralph Payne-Gallwey
Catapult Plans
Catapult Plans
Trebuchet Plans
Working Models
Catapult History - Ancient Roman Catapults


It is, indeed, impossible to find a complete working plan of any one of these 
old weapons, a perfect design being only obtainable by consulting many ancient 
authorities,  and,  it may be  said,  piecing  together  the  details  of  construction  they individually give.

We have no direct evidence as to when the engines for throwing projectiles 
were invented. 

It does not appear that King Shalmaneser II. of Assyria (859-825 B.C.) had 
any, for none are depicted on the bonze doors of the palace of Baliwat, now in the
British  Museum,  on  which  his  campaigns  are  represented,  though  his  other 
weapons of attack and defense are clearly shown.

The earliest allusion is the one in the Bible, where we read of Uzziah, who 
reigned  from  B.C.  808-9 to  B.C.  756-7.  ‘Uzziah  made  in  Jerusalem  engines 
invented  by  cunning  men,  to  be  on  the  towers  and  upon  the  bulwarks,  to  shoot arrows and great stones withal.” (2 Chronicles xxvi. 15.)

Diodorus tells us that the  engines were first seen about 400 B.C., and that 
when  Dionysisu  of  Syracuse  organized  his  great  expedition  against  the 
Carthaginians (397 B.C.) there was a genius among the experts collected from all 
over  the  world,  and  that  this  man  designed  the  engines  that  cast  stones  and 

From the reign of Dionysius and for many subsequent centuries, or till near 
the close of the fourteenth, projectile-throwing engines are constantly  mentioned 
by military historians.

But it was not till the reign of Philip of Macedon (360-336 B.C.) and that of 
his son  Alexander the Great  (336-323 B.C.) that their improvement was carefully 
attended to and their value in warfare fully recognized.

As before stated, the Romans adopted the engines from the Greeks.
Vitruvius and other historians tell us this, and even copy their descriptions 
of them from the Greek authors, though too often with palpable inaccuracy.
To  ascertain  the  power  and  mechanism  of  these  ancient  engines  a  very 
close study of all the old authors who wrote about them is essential, with a view to 
extracting  here  and  there  useful  facts  amid  what  are  generally  verbose  and 
confused references.

There is no doubt that the engines made and used by the Romans after their 
conquest  of  Greece  (B.C.  146),  in  the  course  of  two  or  three  centuries  became inferior to the original machines previously constructed by the Greek artificers.There  efficiency  chiefly  suffered  because  the  art  of  manufacturing their important parts was gradually neglected and allowed to become lost.


FIG. 2. – A SIEGE.
Criticism.-The picture is open to the spectator in order that he may see both defenders and besiegers at work. 
The besieged have just cast a stone from a catapult.  The stone is falling on the movable tower belonging to the attacking side. From Polybius.  Edition 1727.



For  instance, how to  make  the  skein  of sinew  that  bestowed  the  very  life 
and existence on every projectile-casting engine of the ancients.

The tendons of which the sinew was composed, the animals from which it 
was taken, and the manner in which it was prepared, we can never learn now.
Every  kind  of  sinew,  or  hair  or  ropes,  with  which  I  have  experimented, 
either breaks or loses its elasticity in a comparatively short time, if great pressure 
is applied.  It has then to be renewed at no small outlay of expense and trouble.
Rope skeins, with which we are obliged to fit our models, cannot possibly equal in 
strength and above all in elasticity, skeins of animal sinew or even of hair.

The formation of the arm or arms of an engine, whether it is a catapult with 
its single upright arm or a ballista with its pair of lateral ones is another difficulty 
which cannot now be overcome, for we have no idea how these arms were made to 
sustain the great strain they had to endure.

We know that the arm of a large engine was composed of several spars of 
wood and lengths of thick sinew fitted longitudinally, and then bound round with 
broad strips of raw hide which would afterwards set nearly as hard and tight as a 
sheath of metal.

We know this, but we do not know the secret of making a light and flexible 
arm of sufficient strength to bear such a strain as was formerly applied to it in a 
catapult or a ballista.

Certainly,  by  shaping  an  arm  of  great  thickness  we  can  produce  one  that 
will not fracture, but substance implies weight, and undue weight prevents the arm 
from acting with the speed requisite to cast its projectile with good effect.
A  heavy  and  ponderous  arm  of  solid  wood  cannot,  of  course,  rival  in 
lightness and effectiveness a composite one of wood, sinew and hide.

The  former  is  necessarily  inert  and  slow  in its  action  of  slinging  a  stone, 
while the latter would, in comparison, be as quick and lively as a steel spring.
When the art of producing the perfected machines of the Greeks was lost, 
they were replaced by less effective contrivances.

If  the  knowledge of  constructing  the  great  catapult  of  the  ancients  in  its 
original  perfection  had  been  retained,  such  a  clumsy  engine  as  the  medieval 
trebuchet  would  never  have  gained  popularity.  The  trebuchet  derived  its  power from the gravity of an immense weight at one end of its pivoted arm tipping up the other end, to which a sling was attached for throwing a stone.

As regards range, there could be no comparison between the efficiency of a


Catapult History - Ancient Roman Catapults
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