Criticism.-This engine was moved into position on rollers and then props were placed under its sides to adjust  the range of the projectile.

The end of the arm was secured by the notch of the large iron catch and was released by striking down the handle of the catch with a heavy mallet.

The arm is, however, too long for the height of the crossbar against which it strikes and would probably break off at its centre.

The hollow for the stone is much too large, as a stone big enough to fit it could not be cast by a weapon of the dimensions shown in the picture.

The medieval catapult was usually fitted with an arm that had a hollow or cup at 
its upper end in which was placed the stone it projected, as shown above in fig. 5.¹

I  find,  however,  that  the  original  and  more  perfect  form  of  this  engine,  as 
employed  by  the  Greeks  and  ancient  Romans,  had  a  sling,  made  of  rope  and leather, attached to its arm.² (Fig.6.)

¹   See also The Crossbow, etc., Chapters LV., LVI., illustrations 193 to 202.

² In  medieval  times  catapults  which  had  not  slings  cast  great  stones,  but  only  to  a  short  distance  in comparison  with  the  earlier  weapons  of  the  same  kind  that  were  equipped  with  slings.  I  can  find  no

The  addition  of  a  sling  to  the  arm  of  a  catapult  increases  its  power  by  at 
least  a  third.  For  example,  the  catapult  described  in  Chapters  LV,.  LVI.,  of my book,1 will throw a round stone 8 lbs. in weight, from 350 to 360 yards, but the 
same engine with the advantage of a sling to its arm will cast the 8-lb. Stone from 
450 to 460 yards, and when its skein is twisted to its limit of tension to nearly 500
yards.

If the upper end of the arm if a catapult is shaped into a cup to receive the 
stone, as shown in fig. 5,, the arm is, of necessity, large and heavy at this part.
If, on the other hand, the arm is equipped with a sling, as shown in fig. 6,, it  can  be  tapered  from  its  butt-end  upwards,  and  is  then  much lighter and recoils with far more speed than an arm that has an enlarged extremity for holding its missile.

When the arm is fitted with a sling, it is practically lengthened by as much 
as  the  length  of  the  sling  attached  to  it,  and  this,  too,  without  any  appreciable increase in its weight.

The longer the arm of a catapult, the longer is its sweep through the air, and 
thus the farther will it cast its projectile, provided it is not of undue weight.
The difference in this respect is as between the range of a short sling and 
that of a long one, when both are used by a school-boy for slinging pebbles.
This increase of power conferred by the addition of a sling to the arm of a 
catapult is surprising. 

A small model I constructed for throwing a stone ball, one pound in weight, 
will  attain  a  distance  of  200 yards  when  used  with  an  arm  that  has  a  cup  for holding the ball, though when a sling is fitted to the arm the range of the engine is 
at once increased to 300 yards.

The only historian who distinctly tells us that the catapult of the Greeks and 
Romans had a sling to its arm, is Ammianus Marcellinus.  This author flourished 
about  380 AD.,  and  a  closer  study  of  his  writings,  and  those  of  his 
contemporaries, led me to carry out experiments with catapults and ballistas which 
I had not contemplated when my work dealing with the projectile engines of the 
Ancients was published.

allusions  or  pictures to  show  that  during  this  period  any  engine  was  used  with  a sling  except the trebuchet, a  post-Roman invention. All evidence goes to prove that the secret of making the skein and other important parts of a catapult 
was  in  a  great  measure lost  within a  couple  of  centuries after  the Romans copied  the weapon from  their  conquered enemies the Greeks, with the result that the trebuchet was introduced for throwing stones.

The catapult was gradually superseded as the art of its construction was neglected, and its efficiency in sieges was therefore decreased.

The catapults of the fifth and sixth centuries were very inferior to those described by Josephus as being used  at the sieges of Jerusalem and Jotopata (A.D. 70, A.D. 67).

¹  The Crossbow, etc.