The Gastaphetes, or belly shooter.

Introduction

Comitatus shows consist of many different elements, not least infantry, cavalry and artillery. Reconstructed artefacts are not just shown but demonstrated in an educational and entertaining display. This normally involves learning new skills and how to use reconstructed equipment.



Greek shows allow us to portray a wide range of infantry types and their weapons. The cavalry element of the show is perhaps the most challenging with elements of trick riding involved such as vaulting. But in terms of equipment, the gastaphetes is perhaps the hardest to master.


History

“The history of Classical artillery is a minefield of terminology, conflicting interpretations and little known writers. As Alan Wilkins noted, Greek artillery engineers are the first to use cube root equations, straight and rotary ratchets, winches, multiple pulley systems, horizontal sliding dovetails, flexible universal joint bearings, screw threads and the massive energy stored in stretched and twisted rope-springs. By around 300 BC Dionysius of Alexandria designed a repeating bolt shooter with a double-chain drive, a cam mechanism translating linear into rotary motion, and automatic systems for feeding bolts and engaging and releasing the trigger. They had plans for catapults powered by bronze springs or compressed air pistons!

The Greek katapaltes comes from the verb katapallein meaning "to hurl down". Heron of Alexandria in Ktesibiou Belopoiika 74 writes that "the object of catapult construction is to project the missile over a great distance and strike a hard blow at a given target". They must be able to exceed the power achieved by an archer's muscles, who can be trained to shoot 180lb bows in extreme cases.

Diodorus Siculus writes that in 399 BC the catapult, katapeltikon, was invented under the patronage of Dionysius I, the tyrant of Syracuse. But the Roman engineer Heron of Alexandria explains in "Ctesibius's manufacture of missle weapons", Ktesibiou Belopoiika, that this weapon was inspired by an earlier weapon, the gastaphetes or belly shooter. Biton, an author who is sometimes questioned, cites two forms of an advanced gastraphetes accredited to Zopyrus from Tarentum at the end of the 5th century BC. These machines were proper artillery pieces with stands, winches and crews, showing a development towards the torsion catapult.


Description

The belly shooter was built around a powerful symmetrical composite bow, consisting of a wooden core sandwiched between a layer of horn and a layer of sinew. The horn was glued in the belly of the bow, towards the operator, and resisted compression. The sinew glued on the back or outside of the bow stretched but wanted to return to its natural state. So the finished bow acted as a spring made of natural materials, far stronger than the human hand could draw, and would take a considerable time to make. The belly bow was named because of the concave rest at the rear of the weapon upon which the shooter rests their stomach while spanning the machine. The stock of the weapon consists of the syrinx or pipe, and the diostra or slider. The bow and concave rest are fixed to the pipe, while the slider is dovetailed on top of it. The slider moves forwards and backwards with the trigger mechanism attached to the rear of it. The general form of the trigger assembly is given in a diagram by Heron, and was worked out by Schramm, although no specific trigger parts for Greek and Roman artillery have been identified. The bowstring is held by a claw mirroring the archers fingers, and is released by the trigger sometimes know as the snake. As the slider is forced into the pipe, pawls on either side of the pipe move backwards along two toothed ratchet-bars, locking into the ratchets as the weapon is spanned.

The operator moves the slider forwards so the bow string can be held by the claw and trigger. Then the front of the slider must be fixed against a wall or the ground while the operator throws their weight into the stomach rest. This is not an easy process and the power of the bow can literally lift a grown man off his feet. Both weight and muscle must be used to span the weapon. The slider is forced back along the pipe pulling the bow string back with it. With the weapon at full draw the operator can really sense the power held within the weapon. The arrow is placed in the groove cut along the whole length of the slider. When the trigger is pulled backwards, the claw releases the bow string, shooting the arrow from the weapon.


Early Academics

Sir William Tarn believed the gastraphetes was the weapon invented by Dionysius's engineers, and Eric Marsden based his study of ancient artillery upon this assumption. However Major General Erwin Schramm preferred to believe that Diodorus had meant the torsion catapult was the invention of 399 BC and so the belly shooter was older. But Biton actually calls the belly shooter a catapult or katapeltikon, suggesting that perhaps this little known weapon was presented to Dionysius in 399 BC, but invented earlier. Indeed Biton describes two older machines designed by Zopyrus, one the so-called mountain gastraphetes at Cumae in around 421 BC, and another at Miletus in around 401 BC which could shoot two bolts 1.85m in length and 3.6cm in diameter. Discharging two bolts would severely limit the range of the weapon, perhaps putting the volume of missiles over the range of missiles. The first had a 1.5m stock and a 2.2m bow, the second had a 2.2m stock attached to the 2.8m bow. Both of these heavy machines were spanned by a winch pull-back system and were placed on stands. Zopyrus's two bolt machine is reproduced in an 11/12th century manuscript illustration, showing the component parts from different angles. As is often the case with manuscript drawings it is hard to tell how much of the original design is faithfully reproduced. By around 340 BC torsion catapults would be developed probably by the engineers of Philip and Alexander of Macedonia, but that is another story.


Reconstructions
The major difficulty in constructing the belly bow is the bow itself, and our inability to accurately reproduce the bow limits the value of the reconstruction. However the weight and utility of the belly bow can be estimated.

Schramm built a belly bow using steel bow arms riveted to the pipe, however sprung steel does not really appear until the fourteenth century AD. His example and his other reconstructions have been admired by generations of enthusiasts.

Our version was built by Leo Todeschini aka Tod Todeschini Bsc.(Hons) MDes.Eng.(RCA)DIC. Tod has years of experience in reproducing items and machinery from the past. Making a composite bow which could safely generate the power needed would take time, skill and money, so a commercially available bow was used instead. The Kassai Bear symmetrical bow is a well known "off the shelf" model which is designed to cope with draw weights of up to 110lb. The ears of the bow had to be shortened to take the string, and new knocking points were cut and strengthened by metal pins. This will have affected the performance of the weapon, making the draw much stiffer.

The bow was secured to the oak pipe by rope to a large button under the weapon, making it easily dismountable and tightened by opposing wedges. This button provided an ideal rest upon which the weapon could be balanced on a wall, acting almost like a ball mounting.



Wilkins suggested that an "average" person could achieve 150 lb stomach pressure, with perhaps a heavier operator achieving 185- 200 lb. However the Kassai 90 lb bow could be barely spanned by a strong man of 76.2 kg and 175.3cms in height. Indeed the power of the bow could actually lift the operator off his feet. A smaller, lighter 5th or 4th century operator would surely have struggled. Could it be that the twin handles either side of the stock could be for two operators to fully span the bow, while only one shoots it? An interesting question posed only half in jest. However the bow can be easily dismounted and using it as a hand bow I could only pull it to half draw, demonstrating the advantage the frame gives the operator. The end of the wooden slider does suffer slight damage when the weight of the weapon is pushed down upon it, but resting the weapon on a fur to span it reduces wear and tear.

The stock measures 97cm while the cut down bow measures 1.2m. The weapon weighs 4.6 kg. Duncan B. Campbell suggested the weapon would need to be rested on a wall or a sort of musket rest, but instead it can be carried easily and aimed from the waist. The performance of the weapon is dictated by the power of the bow but also the draw length of the slider, much as an archer's draw length is limited by the length of their bow arm. An average draw length for an archer is around 72cm, while our reconstruction has a draw length of 45cm. This severely limits the weapon in terms of generating power.

The arrows are 80cm in length, and weigh 66g. When shot by an archer the Bear does shake in the hand, and when mounted on the pipe there is a definite recoil when shot. This came as a surprise and the curved rear stock which fits into the operators belly is a useful addition, not just for loading, but for absorbing the recoil. While the weapon could be held and aimed from the shoulder, the recoil and any potential breakage could conceivably be dangerous to the operator.

The 12mm shaft narrows on two sides at the knock to fit into the claw of the trigger mechanism, also reducing drag through the air. The arrow head is a simple bodkin design.


Conclusions

There is no evidence for the ranges achieved by Dionysius' catapults, although some conclusions have been made based on the killing grounds within fortresses. But they certainly made an impression on those who witnessed their power. Plutarch writes about the Spartan king Agesilaus who on seeing the new artillery in around 368/367 BC exclaimed, "By Heracles! A man's courage in battle is no use anymore". Dionysius had sent his machines to help the Spartans defeat the Arcadians and Argives in what Xenophon called the "tearless victory". The artillery had destroyed the enemies will to fight, at ranges beyond which they could reply.

Marsden suggested the range of a bolt would be around 250m, just sufficient to out range an average archer. I am distrustful of weapons tests, since I generally doubt their objectivity. But we did conduct some tests to measure the belly bow relatively against a hand held bow. I used a 67lb Grozer biocomposite made from horn, wood and sinew with an excellent cast. It regularly outdistances my 90lb self bow made of American yew, and the Comitatus Roman iron-framed ballista with a draw weight of around 750lb and 85g bolts. The ballista has a range of around 200m, about half of an original.

In truth I expected the bow to outrange the belly bow but that was not the case. With light 40g wooden arrows the Grozer achieved 220m, and with even lighter bamboo arrows 230m. But the belly bow was able to achieve 240m with much heavier arrows which surprised us all. The heavier missiles also penetrated the ground to great depth, while the bamboo arrows were merely falling from the sky. If nothing else the tests showed the belly bow could deliver a heavy arrow a considerable distance. It would probably not be out ranged by archers, backing up Marsden's assertion.

The weapon is certainly easy to carry, deploy and aim, although a second operator can help with securing the pawls on either side of the pipe. Two shots could be achieved each minute, with the operator instinctively aiming the bow from their waist, as an archer instinctively aims their bow when pulling it back to their chest or ear. While a 15th century English long tiller crossbow can be rested on the shoulder and aimed along the grove for the bolt, shooting the belly bow in this manner would be unadvisable.

It allows a relatively unskilled man to use a viable missile weapon without years of training. The power of the belly bow is limited by the weight and strength of the operator, and the draw length of the weapon. It can deliver a heavy arrow at long distances. But perhaps its greatest asset is its novelty value, with many enemies being unsure of its power or potential.



Select reading list

Campbell D.B. Greek and Roman Artillery 399 BC- AD 363. Oxford, Osprey. 2003.

Marsden, E.W. Greek and Roman Artillery: Technical Treatises. Oxford, Clarendon Press, 1971.

Schramm, E. Die antiken Geschutze der Saalburg, Berlin: Weidmannsche Buchandlung, 1918, reprinted Saalburgmuseum, 1980.

Tarn, W.W. Hellenistic Military and Naval Developments. Cambridge: Cambridge University Press, 1930.

Wilkins, A. Roman Artillery Princes Risborough, Shire archaeology, 2003.