Many years ago, long before I joined The Roman Military Research Society (or RMRS), a teacher inspired his pupils to build a catapulta, or bolt-shooting Roman period artillery machine. I guess the project was in part a history lesson combined with developing practical engineering skills. Whatever the motive, the resulting machine was eventually gifted to the Lunt Roman Fort in Baginton near Coventry. When I first encountered this machine it was part of a static display in the Fort's small horea (granary) museum, and there it sat, unobtrusively, for many years.
A recent refurbishment of the Lunt Fort's granary saw the catapult placed in storage where it could easily have remained, forgotten. Except for the fort's Engagement and Development Manager, Paul Thompson, who decided the machine would be an ideal addition to the new displays and, if working, could demonstrate how it works, and shoots, to school parties and other visitors.
So, who could do the repairs? Enter the RMRS or more specifically Len Morgan and myself. For my part, my knowledge and understanding of ancient Greco-Roman artillery has been inspired and much improved by three mentors: Alan Wilkins FSA, Len Morgan and the late Tom Feeley. Over decades of research and practical experimentation, these "three wise men" have done much to promote the wider understanding of such machines. Alan, for example, has spent a lifetime deciphering the manuscripts written by authors such as Philon, Biton and Vitruvius who recorded their thoughts and their technical treatises in ancient Greek or Latin.
Sadly, what survives for us to work with today are often copies made in the past by scribes practicing or perfecting their craft. Since such men were not engineers, crucial textual information can be mistranslated, transcribed incorrectly or omitted altogether. Alan, therefore, has been instrumental in identifying and correcting various errors or deducing the often essential but missing information. Together with Len and Tom, both experienced engineers, models and full-size machines have since been recreated to test theories and demonstrate these artillery pieces to academics and the wider public.
A great deal of work had already gone in to getting the machine to the stage shown opposite. The trigger mechanism was removed and renovated to improve its operation and avoid undue damage to the bowstring. A new pull back cord was fitted connecting the windlass to the trigger mechanism, itself attached to the slider. Even the pawls on the trigger assembly were chamfered so they did not foul the ratchet when the slider is pushed forward.
Most importantly, as the spring washers were of turned wood, these were reinforced with steel pins and collars to resist the forces generated when spanning the weapon and when shooting. This measure proved to be a good move as a crack quickly appeared when the weapon was tensioned for the first time. The original wooden levers were replaced with mild steel versions. This was necessary because it is around these levers, or bars if you prefer, that the cord is wound to create the spring bundles.
Into the spring bundles the bow-arms are inserted, as can be seen opposite. Rotating and pinning the washers in position imparts a twist to the cord bundle. Pulling back the bow-arms twists the bundles even further increasing the potential energy stored in each spring. This is where such torsion engines get the power to project missiles. The penultimate task was to fit a new bow-string, whipping and sewing the ends together to form the loops that hook onto the bow-arms. Finally, the vane ends of the bolts were reduced to fit between the fingers of the trigger such that when loaded they rest cleanly against the bow-string.
With all the work complete it was testing time. The materials used in its original construction were never going to make the machine particularly powerful but the ol' girl still shoots. So, all being well, visitors and especially school parties will soon get to see the Lunt Fort's cataputa in action once more.