BaatzArtillery

Recent Finds of Ancient ArtilleryAuthor(s): Dietwulf BaatzReviewed work(s):Source: Britannia, Vol. 9 (1978), pp. 1-17Published by: Society for the Promotion of Roman StudiesStable URL: http://www.jstor.org/stable/525936 .Accessed: 04/05/2012 03:43

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Recent Finds of Ancient Artillery By DIETWULF BAATZ

UR knowledge of ancient artillery derives primarily from several ancient technical texts. The most important among them are

the works of Philon, Heron and Vitruvius.1 Taken in combination, these texts are sufficiently detailed to allow reconstruction of functioning artillery- pieces, and the first reconstructions of catapults were made as early as the middle of the nineteenth century, long before any actual find was known.2 The second source for our knowledge of ancient artillery consists of representations of catapults found on Greek and Roman reliefs.3 In spite of their small number these reliefs are a significant complement to the written texts, not only because they show technical detail which might otherwise be controversial, but also because most of them can be dated within narrow bounds and in this way give some hints at the direction of development of ancient artillery. But the chances of finding new texts or new reliefs are very small. So actual finds of ancient catapults in archaeological excavations constitute a third source, which will gain increas- ing importance, because there are fair chances of finding remains of catapults at a number of sites.

The first remains of a catapult came to light in 1912 in Ampurias (Spain). A hoard of weapons was found in an arsenal near the South Gate of the Neapolis of Emporiae, the ancient site at Ampurias. The hoard was deposited in the first half of the second century B.C. Among its contents were the metal parts and fittings of the timber frame of a small arrow-shooting catapult (euthy- tonon, catapulta, scorpio) of typical Hellenistic design. The excavators at first interpreted these as parts of an ammunition-carriage.4 Only two years later they were recognized by W. Barthel as components of a catapult and were then published with the help of E. Schramm, who had just com-

pleted a programme of catapult-reconstructions after the ancient texts.5 Schramm was amazed to see how exactly the dimensions of the Ampurias catapult corresponded to those given in the written ancient sources.6 The find also yielded some details not mentioned in the texts.7 During the First World War Schramm built a full-sized reconstruction of the Ampurias catapult which functioned quite satisfactorily and may be regar- ded as the best catapult reconstruction so far built because it is based on both texts and finds.8

The example of this first artillery-find of 1912 demonstrates the difficulties an excavator has to face in identifying remains of ancient artillery. These finds are very rare: most archaeological

1The texts are collected (with English translation) in E. W. Marsden, Greek and Roman Artillery, Tech- nical Treatises (Oxford, 1971). A disadvantage of this edition is the omission of the ancient text-diagrams, which are quite important and must be looked for in other editions, for instance: C. Wescher, Poliorcitique des Grecs (1867).

2The first reconstructions were built by Dufour and de Reffye in France by order of Napoleon III. Photos in Archaeologia Aeliana2 xxiv (1902), 72-3, figs. 3-4.

'3E. Schramm, Die antiken Geschiitze der Saalburg (1918), 30-9.

SJ. Puig Y Cadafalch, Annu. Inst. d'Estudis Cata- lans 4 (1911-12), 672, fig. 2.

'P. Bosch Gimpera, Annu. Inst. d'Estudis Catalans 5 (1r93-r4), 841-6.

6 Schramm, op. cit. (note 3), 4o-41. SFor instance the holes in the washer and in the

counter-plate, through which retaining-pins could be pushed: Schramm, op. cit. (note 3), 43-4; cf. E. W. Marsden, Greek and Roman Artillery, Historical Development (Oxford, 1969), 29, fig. 15.

SThe reconstruction is still preserved in the Saal- burgmuseum, Bad Homburg, Germany. For a photo, see G. Webster, The Roman Imperial Army (1969), pl. 29.

I

2 DIETWULF BAATZ

• •

iron lever 0 0.1 0.5 1,0m bronze washer

-bz<--

frame

o o 0 string-- arm

case slider

trigger

- arm frame

- bronze washer

windlass claw arm

, \(<-- frame

slider

case

<-bronze washer 0

FIG. I. Arrow-shooter (catapulta) of Vitruvius, designed for shooting arrows of three feet (reconstruction by Schramm). Scale 1:25.

textbooks do not mention them,9 and so some of the curiously-shaped metal objects may be left unpublished in forgotten corners of museums. For many decades after the Ampurias find of 1912 no new catapult-finds were published, until in the years 1968 and 1969 N. Gudea excavated two small late Roman forts at Gornea and Orgova near the Iron Gate of the Danube in Roumania. In the projecting comer-towers of these forts some metal parts of catapults were found. Another catapult

was unearthed 1972 during excavations near the North Gate of Hatra (Iraq), conducted by W. I. Al-Salihi of the Directorate General of Antiqui- ties, Baghdad. The finds of Hatra, Orgova and Gornea are the subjects of the present paper.

As a preliminary, the construction and functioning of a two-armed torsion-machine may be des-

9 Even in Marsden's books, op. cit. (notes I and 7) no photos and no drawings of the very important iron fittings of the Ampurias catapult-frame are given.

RECENT FINDS OF ANCIENT ARTILLERY

cribed. FIG. 1 shows a two-armed arrow-shooter of late Hellenistic type. These engines were powered by two springs consisting of bundles of cords made of hair, or sometimes of sinew, kept under tension. The cords of each spring were wound around an iron lever at either end of the spring. The levers in turn rested on bronze washers. Both springs were held in a timber frame, which was reinforced by metal fittings. The two wooden arms of the arrow-shooter were inserted into the springs, and were connected by a sinew-cord, acting as a bow-string. The centre of the string was engaged by an iron trigger- mechanism, consisting of claw and trigger. Both parts were mounted on the slider, which could move freely in a groove in the case or stock. These parts, too, were made of timber. In order to fire the catapult, the slider was first pulled back by a windlass mounted on the end of the case. By this movement the sinew bow-string was also drawn back, and with it the two wooden arms. These, being inserted in the cord-bundles, twisted them progressively as the windlass was wound up, thus storing the energy for the shot in the torsion- springs. Next, an arrow was placed on the slider with its end in contact with the sinew bow-string. By pulling the trigger, the bow-string was released

and the arrow fired. Afterwards, the slider was pushed forward again and the bow-string hooked into the trigger mechanism, to prepare the catapult for the next shot.

The two-armed stone-thrower (palintonon, ballista) was of similar construction. The main differences were the bigger dimensions of these machines and the bow-string which took the form of a band. In addition the engine was normally laid at a higher angle of elevation, up to 45 deg- rees, since it discharged its shot in a much higher trajectory than the arrow-shooter except when the latter was being fired at extreme range.

A. THE HATRA BALLISTA

Description Just behind the second tower to the west of the North Gate of Hatra the remains of a comparatively big catapult were found buried under the debris of the adjacent tower and town-wall.1' Originally the engine must have been set on top of the tower from which it will have fallen during a siege. The tower itself (Andrae XIX), one of the

10 The find was first mentioned in Sumer 27 (1971), page g. I saw and measured the remains of the catapult in December 1975 in Mosul Museum (Iraq).

--- --- - ~f ---- - -- - - --- - -- - - - - - - -- -------------------------------------- o1 0 o0o c o

orO O O ~ O O l a o o o a o

oo o o o c o o O O O o O o O O O O o o o.

ooo ooo

0 01

/0 0

0 00

0 0 0 0oo

0 0 0 0 0

0 0 0 0 0 1

0 Oil

LO O O O 01O O O O O O O l

0 0 a 0 0 a 0 0 0 0 0 0 0

0O 0 0 0 0 0 0 0 a 0 0 0 0 0 0 0 0

0 00 0 0

FIG. 2. Hatra ballista. Metal parts of the frame, schematically drawn. Scale I: 2o.

4 DIETWULF BAATZ

A

B

FIG. 3. Hatra ballista. Two different types of corner-fittings (bronze). Scale 1: 75.

series of massive solid stone structures built as additions against the existing town wall, belongs to the last phase of the town's defences (PL. I)."1 As Hatra was destroyed in the middle of the third century A.D., this gives an approximate date for the fall and burial of the catapult.

Only the frame which once held the two torsion- springs was found at Hatra (PL. II-IV A ). No trace survived of the wooden slider and the case with its windlass, or of the base on which the machine was mounted. FIG. 2, which is based on the actual finds of metal fittings and on the excavation photos, gives an idea of the construction of the frame. It was c. 2-40 m wide, 0.84 m high (without corner-fitting and washers) and 0-45 m thick. The frame proper consisted of several different pieces of wood morticed together; but, except for small fragments, nothing of this remained and the dimensions given above are therefore only approximate. There could also have been more transverse pieces between the four long main beams. Analysis of the surviving fragments of timber proved this to be pterocarya fraxinifolia, a tree growing in mountain regions from Asia Minor to Northern Iran.12

The frame (main long timbers and two side stanchions) was covered on the front and sides by sheets of bronze c. 2 mm thick, fixed by nails. Especially to be noted are the two half-round openings in the side-stanchions. As in other tor-

sion-engines, the purpose of these was to accommodate the two arms of the machine. Similar openings have been noted in the frame of the Ampurias catapult,'3 and they are also mentioned in the ancient written sources.'4

All eight corners of the wooden frame will have been fixed with elaborate joints. Each joint was protected and held together by heavy fittings of cast bronze nailed to the frame (FIG. 2 and PL.

IV A). The fittings are of two types, each roughly the mirror-image of the other (FIG. 3). Such fittings have not, so far, been recorded for any other type of ancient artillery and are a peculiarity of the Hatra catapult.

The most characteristic parts of any piece of ancient torsion-artillery are the washers set into counter-plates, and the levers used to tighten the

torsion-springs. The Hatra catapult originally had four washers with four levers. Only three have been found, though all four counter-plates were recovered. The washers were made from cast bronze (PL. III and FIG. 4). Their inner diameter was 17-5 cm at the bottom and 16 cm at the top;

" W. Andrae, Hatra II. Wiss. Ver6ffentl. d. Deutschen Orient-Gesellschaft 21 (1912), 30 ff.

1 I am indebted to Dr M. Hopf (Mainz) and to Dr D. Eckstein (Hamburg) for the identification of the species.

13 Schramm, op. cit. (note 3), 44-5, figs. 16--17 4 Heron, Belopoeica 91-92 (ed. Marsden, note I);

Vitruvius x I11,5.

RECENT FINDS OF ANCIENT ARTILLERY 5

1 5 10cm

FIG. 4. Hatra ballista. Bronze washer. Scale I:4.

the outer diameter was 28 cm. Set into the counter-plate, the washer was I1 -2 cm high (from surface of counter-plate to top of washer). The total height of the washer, including the circular rim going into the central hole of the counter plate, was I2-2 cm. In the wide outer flange of the washer there are 16 holes, each hole having a diameter of 1 cm. The counter-plates have 8 holes, arranged in 4 pairs. Retaining-pins could be pushed through the holes in the flange of the washer into the corresponding holes in the counter- plate, so holding the washers in position once they had been turned sufficiently to give the springs the requisite tension. In the holes of each washer and its counter-plate were traces of up to three iron retaining pins. One of them is visible on PL. III A; also on PL. III B, foreground. The Ampurias catapult was provided with a comparable set of holes and retaining-pins, although there the holes

were arranged differently.15 In the top of each washer were two notches for holding the iron levers. The notches were 3 cm wide and 1.6 cm deep. Below the notches an internal reinforcement- rib was cast in one piece with the washer. These ribs are not mentioned in the ancient sources, nor were they present in the small washers of the Ampurias catapult, but their use in the big washers of the Hatra engine is easily explicable because of the heavy strain put on the washer at this point by the lever. The iron levers were deep- ly corroded, so no exact dimensions could be taken (PL. III A). But the width of the notches on top of the washers is known (3 cm), and this gives the width of the levers. The levers seem to have been about 29 cm long and possibly 6-8 cm high. No remains of the cords (torsion-springs) running around the levers were found.

The counter-plates (PL. III and FIG. 5) were square, having sides 29.0-30-5 cm long. They were made from cast bronze 6 mm thick and each plate was fixed to the frame by four nails in the

10cm

FIG. 5. Hatra ballista. Bronze counter-plate. Scale x1:4.

15 Schramm, op. cit. (note 3), 43-4; Marsden, op. cit. (note 7), 29-30o.

6 DIETWULF BAATZ

corners. The eight holes for holding the retaining- pins passing through the flanges of the washers have been mentioned already; they were arranged in four pairs. The circular rim on the bottom of the washer fits neatly into the central opening of the counter-plate, but not tightly, so that the washer can be turned easily in the opening. In order to fix the counter-plate more securely, the sides of the central opening extend downward like a cylindrical sleeve to fit into the hole in the timber frame. Inclusive of this sleeve the counter- plate is 3-5 cm high. The diameter of the central hole is 20.9 cm on the upper flat side of the plate, upon which the washer rests. The internal diameter at the bottom of the sleeve is slightly less, being only 20.6 cm. All four counter-plates are bent a little so that the corners are 1-2 mm higher than the edge of the central opening. This may have been caused by the pressure exerted on the washers by the torsion-springs. Counter-plates for washers are mentioned by Heron and Philon.16

In order to pull back the arms of the catapult there must have been both a wooden case with windlass, and a slider, similar to the corresponding parts of the arrow-shooter (FIG. I). The case was always attached to the centre of the two lower long main beams joining the bottom of the frame. Nothing remained of the case, but exactly in the centre of two of the long beams of the frame (which were certainly the lower pair), were found strong iron bolts and two heavy iron bands (PL. II A, left side of the frame). In all probability they fixed the case to the frame. If this is right, the machine will have fallen with its front in the ground and its case or stock sticking up in the air. The correctness of this assumption is strength- ened by the observation that only one side of the frame, certainly the front, was protected by bronze sheets and this was on the bottom when excavated. (PL. II A). This would also explain the absence of the case, and the metal parts of the windlass at its end, among the finds.

There was a number of other finds made near- by and more or less certainly connected with the catapult:

1. Five sturdy bronze rollers with iron axles (FIG. 6). They were 3-4 cm long and 4-8 cm in diameter. Their use is suggested by the written sources, which state that ropes used for pulling the sliders of the larger stone-throwers backwards

and forwards by means of pulleys or other devices17 should pass over rollers.

2. Rectangular bronze sheet, consisting of three pieces nailed together side by side on a piece of wood now lost. The dimensions overall are 41.5 cm wide, 49-5 cm long and 0-3 cm thick. The nails were placed around the periphery. As one excavation photo shows, the sheet was found under the ballista, and not in contact with the frame, so it may not be part of the machine.

3. Two smaller rectangular bronze sheets with a central rectangular hole. The length of the sides are 14-3 (14-7) and 13.0 (13-3) cm (dimensions of

FIG. 6. Hatra ballista. Bronze roller with iron axle. Scale I:2.

second sheet in parentheses). The central hole is 4'9 by 4o0 cm. Eight nail-holes are set round the periphery of the sheets, so these sheets also were once mounted on wood. Their position on the ballista is not known.

4. Various pieces of iron, all of them heavily corroded. One, in the form of a hook, was possibly the claw of the trigger-mechanism, as it shows traces of an iron axle.18 There are other bits of iron which may also have been parts of the catapult: nails, cramps, fittings, and a piece of iron

* Heron, Belopoeica 97 (ed. Marsden, note I), Philon, Belopoeica 57 (ed. Marsden).

17 Heron, Belopoeica 84-85 (ed. Marsden, note I). '8 Heron, Belopoeica 76 and i i (ed. Marsden, note

I).

RECENT FINDS OF ANCIENT ARTILLERY

sheet with two rods holding a retaining-pin. The interpretation of all these parts is much impeded by the deep corrosion. Other iron objects were definitely not part of the engine (a shield-boss and three large bolt-heads of different sizes).

Furthermore, in the Hatra room of Mosul Museum there are a number of bronze finds on display, which must be the components of another catapult: two cast bronze corner-fittings of a type similar to FIG. 3 and two bronze rollers resembling the roller shown in FIG. 6. Both corner- fittings and rollers are smaller than the Hatra finds so far discussed, and represent a smaller piece of artillery, but presumably constructed in exactly the same way.

Characteristics and Calibre As stated above, the Hatra catapult was a two-

armed torsion-engine. Because of its size the machine must have been a stone-thrower. The Latin term for a two-armed torsion stone-thrower, used for instance by Vitruvius, was ballista.19 As no other ancient stone-thrower has so far been found, our knowledge of these machines is derived from the ancient literary sources, especially the works of Heron, Philon and Vitruvius.20 These writers describe, with minor differences, the type of stone- thrower that was developed during the Hellenistic period. They give special calibration-rules and formulae which allow one to calculate the dimensions of the engine suitable for firing a missile of given weight, the measurements of all parts of the ballista being given as multiples or fractions of a specific module. Conversely it is possible by using the same formula to calculate the appropriate missile-weight for a particular ballista from its dimensions. These formulae are, of course, only valid for the Hellenistic type of stone-thrower described by the authors mentioned above.

The Hatra ballista, however, was built centuries after the period of these authors, and, whether because of technical progress or of adaption to special conditions, represents a type differing in many respects from the machines described by them. The frame has completely different proportions, and is both wider and lower than the frames of the Hellenistic stone-throwers. Again, details of construction vary considerably. There was for instance no peritretos, a wooden sub-component upon which each counter-plate and washer were

mounted within the frame. The torsion-springs, too, must have had very different proportions, being much shorter but thicker than the springs of Hellenistic stone-throwers. The ratio of diameter to length of a torsion-spring is 1: 87 in the Vitruvian ballista, but only 1: 67 for the Hatra stone-thrower (the length being reckoned as the distance from the top of the washer to the top of its opposite number, the diameter as being that of the hole of the washer). All these differences pre- vent us from applying the calibration-formulae given by the ancient sources to the Hatra ballista. Consequently it is difficult to determine the weight of missile for which this ballista was designed.

One possibility of finding out the shot-weight of the Hatra ballista is to compare the volume of one of its torsion-springs to that of a torsion-spring of a Hellenistic stone-thrower. As the torsion- springs store the energy used to propel the missile, so they determine the power of the engine to which they belong and, accordingly, the appropriate missile-weight. The volume of a torsion- spring is directly proportional to the energy it is able to store.21 One torsion-spring of the Hatra ballista will have had a volume of 21-7 litres (length 108 cm, diameter 16 cm). Looking through the list given by Vitruvius we find the ten- pound stone-thrower having torsion-springs of 22-2 litres each22 which is very close to the spring- volume of the Hatra ballista. So we may conclude that the power of the Hatra ballista was approxi, mately equivalent to that of the ten-pound ballista of Vitruvius (10 Roman pounds = 3-27 kg). In antiquity this was a medium rather than a large stone-thrower and machines of this size must have been common.

The ten-pound stone-thrower of Vitruvius was built according to a module of 8 digits (equal to half a Roman foot = 14-8 cm).23 All measure-

1 In later Latin (for instance in Ammianus and Vegetius) there was a change of terminology, the arrow- shooters appearing now as ballistae and the stone- throwers as scorpiones or onagri. Behind the change of terminology there was also a change of construction, cf. Marsden, op. cit. (note 7), i88 f.

20 See note i. 21In comparing the torsion-springs of two different

catapults we assume the quality of the hair-rope was about the same.

2"Length 8-7 modules, diameter I module; the module being I Roman foot (which is 14-8 cm), this gives a length of 128.8 cm and a diameter of 14.8 cm.

" Vitruvius x. 11,3.

8 DIETWULF BAATZ

S1 2m

FIG. 7. Hatra ballista, Tentative reconstruction. Scale I:30.

ments of the ballista are given as multiples or fractions of this module. In spite of all the differences of construction some measurements of the Hatra ballista seem to be identical with the corresponding measurements of the ten-pound ballista of Vitruvius. This is the case with the lever, which should have a width of 1/5 module.24 One-fifth of half a Roman foot comes to 2-96 cm. As we have noted, the lever of the Hatra ballista must have been 3 cm wide. The height of the washer should be three-quarters of the module according to Vitruvius, which gives a height of 11-1 cm. The washer of the Hatra ballista is

11.2 cm high.

The similarity of these measurements confirms our opinion that the Hatra ballista was designed for shooting stones of ten Roman pounds. It also indicates a connexion between the artillery described by Vitruvius and the Hatra ballista. Pos- sibly the Hatra ballista was built after a set of formulae and instructions developed from the text of Vitruvius. Furthermore the dimensions of the frame of the Hatra ballista are approximately multiples of the Roman foot: the frame is roughly 8 feet long, 3 feet high and one and a half feet deep, while the centres of the torsion-springs are

6 feet apart. The Hatra ballista, therefore, was probably a Roman machine or at least a ballista built under Roman influence.

Reconstruction of the Hatra ballista

FIG. 7 gives a side view of the ballista as it may have looked. On the front side the frame was covered by bronze sheets, possibly as a protection against fire-arrows. The cord-bundle of one torsion-spring is visible as well as one of the wooden arms that has been inserted into it. The stock with slider and windlass, and the base (none of which survive) have been reconstructed according to the precepts given by Philon, Heron and Vitruvius. The dimensions of these parts are those of the ten-pound ballista of Vitruvius. The overall dimensions of the ballista are shown clearly by comparing it with the man who is using the windlass to draw back the slider.

Ancient Artillery in Hatra

Founded probably in the first century B.C., Hatra remained for a long time the centre of a semi-

24The width of the lever is given only by Philon, Belopoeica 53 (ed. Marsden, note i).


independent desert kingdom. The city even suc- ceeded in defending her walls (PL. I B) against two Roman emperors, Trajan (I17) and Septimius Severus (198/99), despite the use of the highly advanced siege-machines of the Roman army, including of course artillery. The sources do not describe the first siege in any detail but we are better informed about the assault of Septimius Severus. Cassius Dio also describes the powerful artillery of the Hatreni.25 Their catapults fired at very long range, even striking many of the imperial bodyguard. Some of their machines discharged two missiles at a single shot. The use of artillery by the defenders of Hatra is both remark- able and uncommon, for there are almost no refer- ences to this sophisticated weapon being employed outside the Roman army during the first centuries A.D. Possibly the Hatrene catapults were built under the supervision of a Roman engineer who had a contract with the city or who for some rea- son had taken refuge there.

Dio also mentions the very effective 'flame- thrower' of the Hatreni, which hurled burning bituminous naphta against the Roman siege- machines, destroying nearly all of them except those built by a certain Priscus, who had previous- ly been an engineer in Byzantium.26 The Hatreni may also have used catapults to shoot burning naphta carried by fire-darts,27 and Priscus may have covered his machines with bronze sheets similar to the sheeting of the Hatra ballista as a protection against fire.

The weapons used in the later sieges of Hatra by the Sassanids Ardashir I and Shapur I are not recorded. The attack of Ardashir I (A.D. 227?) may have caused her to incline towards Rome, and possibly as early as during the eastern war of the Emperor Severus Alexander in 232/33 a Roman auxiliary unit was stationed in the city. At any rate two Latin inscriptions found there give positive proof of the presence of cohors IX Mauretanorum under Gordian III (238-244).28 This cohort may have been equipped with artillery. In the first and second centuries A.D. Roman auxiliary units were not normally thus armed, only the legions being provided with torsion-weapons; but from the first half the the third century onwards there are ex- amples of auxiliary cohorts using artillery.29 Furthermore there is the possibility that a legion- ary vexillation was sent with its artillery as a re-

inforcement to Hatra during the late stages of her struggle against the Sassanids.

In summary, the remains of torsion-artillery found at Hatra could be those of a Hatrene weapon, such as are attested by Dio; but a Roman origin cannot be excluded, especially in the present case, as the ballista discussed here clearly belongs to the last phase of the life of the city.

B. THE OR?OVA FIND

Description

During the excavation of the late Roman fort at

Orsova (Roumania) N. Gudea discovered two large iron objects in the projecting south-western corner-tower.30 The two objects were found side by side in a destruction-layer of the end of the fourth century.

1. The first consisted of two heavy rings connected by two iron beams (FIG. 8 and PL. V). Both rings show an extension where the beams were riveted to them. One of the two beams was strongly curved. In the curve the beam was especially reinforced. Furthermore the beams carried two iron loops each, which were of different size. Each of the heavy rings was pierced by four small round holes. Two more holes, probably rectangular, may be conjectured for riveting the two beams to the ring, but because of corrosion they were not dis- cernible. The find was bent and twisted to a certain degree during the destruction of the fort, but in spite of this it seems possible to suggest that the iron beams and loops fastened to them were not arranged radially to the ring as was once sup-

" Cassius Dio 75,11.

26 Cassius Dio 74,11 and 75,11.

27 Fire-arrows (in Latin: malleoli) filled with bitu- men are mentioned by Vegetius Iv, 18; see also Ammia- nus Marcellinus xxIII, 4, 14. Both sources date to the fourth century.

28D. Oates, Sumer 11 (1955), 39 ff.; A. Maricq, Syria 34 (1957), 288 ff.

29 Baatz, Bonner ahrbiicher 166 (1966), 194 ff. An example of an auxiliary cohort being equipped with artillery is the cohors I fida Vardullorum at High Ro- chester: RIB 1280-81.

30N. Gudea, Saalburg-Jahrbuch 31 (1974), 50-59. The finds are preserved in the Institutul de Istorie pi Arheologie at Cluj Napoca (Roumania).

10 DIETWULF BAATZ

18 4 37

0 27 --45 - -

SA IB

o 5 10 15 20cm I I I I I

0

O 4- 79

O

O

FIG. 8. Orpova. Field-frame (KafL3io-,rptov) of catapult, reconstruction-drawing. Below: the bottom ring seen from the upper side. Dimensions given in numm. Scale I:4. IC

RECENT FINDS OF ANCIENT ARTILLERY II

posed.31 The correct arrangement is indicated in FIG. 8C, and is also visible on PL. V. The main dimensions of the find may be seen on FIG. 8. Be- cause of corrosion they are only approximate. The weight of the object is roughly 8 kg.

2. The second find was a long iron rod forged to an arch in the middle. The two ends of the rod were forked (FIG. 9 and PL. II B). On either side of the arch was a small round hole going through the rod. All four ends of the two forks were broken, but at one of the broken ends a single small rectangular hole was preserved intact and appar- ently the beginning of another. The object was considerably bent and twisted (PL. II B). The present overall length is 145 cm but with the broken ends restored it would have been longer. The distance a-b is 124-5 cm (FIG. 9).

Interpretation With the exception of the Gornea finds (see

below), no parallel to the Oryova objects seems so far to have been found at any Roman site. Inter- pretation was stimulated by the works of the late E. W. Marsden, who drew attention to Heron's Cheiroballistra, a comparatively dark and difficult technical text.32 Refuting R. Schneider33 Marsden was able to show that the text describes components of a small two-armed torsion-engine of a type akin to artillery on Trajan's Column (PL. IV B). But only the ancient text-illustrations, which were omitted in Marsden's edition of the Cheiroballistra, decisively indicated the function of the Orsova finds.34 FIG. 10 gives copies of two of the ancient diagrams illustrating the text of the Cheiroballistra. On the left side of FIG. 10,1 are shown two objects which are very similar to the first Orqova find. In the accompanying text they

are termed Ka E(o-rTptUa, which seems to be borrowed from the Latin word campestria. Marsden's translation, which will be followed here, is field frames.35 The field-frames were to hold the cord- bundles of the two torsion-springs of the engine. For this purpose each field-frame, which the text says is to be made of iron, had to carry two bronze washers, each with an iron lever. It follows that the two field-frames were equipped in all with four washers and four levers, and these are shown on FIG. 10,1 to the right.

To hold the two field-frames in position, two iron struts were needed. They are called in the text Ka/LaptOV (arched strut) and KXLkLKLOCV

(ladder strut). On one of the ancient diagrams (FIG. 10,2) these are also represented. Both struts had forked ends. These ends were inserted into the iron loops fastened to the iron beams of the field-frames. In this way an all-metal frame was provided for this type of artillery. On FIG. ii a reconstruction of the cheiroballistra is given which indicates how the components may have been connected; it is discussed below.

31 The first reconstruction-drawing of the find, in Saalburg-Jahrbuch 31 (i974), 56, fig. 8, showed the iron beams and loops standing radially to the ring. After further examination of the original the reconstruction-drawing given here (FIG. 8) seems to be more probable.

32 Marsden, op. cit. (note I), 206-33. 33 R. Schneider, R6mische Mitteilungen 21 (1906),

142-68. 34 Photos of the text-illustrations can be found in

Schneider, op. cit. (note 33); see also the drawn copies in the edition of C. Wescher, op. cit. (note I), 123-34. On the question of the ancient text-diagrams generally: R. Schneider, 'Geschiitze auf handschriftlichen Bil- dern', Ergdinzungsheft zum Yahrbuch der Gesellschaft fiir Lothringische Geschichte und Altertumskunde 2 (1907).

3" Marsden, op. cit. (note I), 222, No. I6.

oi 0oCb

0 10 50cm L I I

- I I I

FIG. 9. Orgova. Arched strut (KaCtqaptov) of catapult, reconstruction-drawing. Scale, 1: 12"5.

12 DIETWULF BAATZ

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FIG. IO. Medieval copies of ancient text-diagrams from Heron's Cheiroballistra (after C. Wescher, note 34).

I. Two field-frames, four washers and four levers. 2. Arched strut (above) and ladder-strut (below), the latter being shown

in two projections combined in one diagram.

Clearly the arched strut with the forked ends shown on the ancient text-rillustration (FIG. 10,2) corresponds to the second Orgova find (FIG. 9). So the Orgova finds may be interpreted as one field-frame and the arched strut of a late Roman torsion arrow-shooter. All other parts of the engine are lost.

The reconstruction of the cheiroballistra (FIG. 11) may also explain why two of the four iron loops of the Orgova field-frame were larger. They must have been the bottom loops, which were to receive the forked ends of the ladder-strut. In contrast to the two upper loops, the bottom ones had to support not only the entire weight of the torsion-spring including the arm, but also that of the arched strut above. In the text and illustrations of Heron's Cheiroballistra all four loops are of equal size. Furthermore the four round holes present in each of the two rings of the Oryova field-frame (FIG. 8C) may be interpreted as having the same purpose as the four pairs of holes in the counter-

plates of the ballista from Hatra (FIG. 5) or the 16 holes in each counter-plate of the Ampurias catapult (note 15). The function of the rings was to act as counter-plates for the lost washers of the catapult. Through these holes, and through corresponding ones in the washers, retaining-pins could be pushed to keep the washers in place. The holes are not mentioned in the text of Heron's Cheiroballistra and not shown on the text illustration (FIG. IO.I).

For an illustration of the Orgova type of arrow- shooter, which was considerably larger than the cheiroballistra, we may use the artillery-pieces shown on Trajan's Column (PL. IV B). The arched strut is a typical component of all of them. Both field-frames are visible in the form of cylindrical elements at the sides of the arched strut. The field- frames proper seem to be covered with metal sheeting as a protection against weather and damp. The arrow-shooters appearing on Trajan's Col- umn are light ones, being served normally by two


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FIG. I I. Reconstruction of Heron's Cheiroballistra.

men. Most of the catapults on the Column are mounted on a carriage (PL. IV B); some others are standing on a base similar to that on FIG. 1.36

Characteristics and Calibre The most important characteristic of the Or?ova type of artillery is the occurence of an all-metal frame holding the two torsion-springs. In this respect the weapon was superior to all Hellenistic catapults, which had timber frames only. The all- metal frame must have had a number of advan- tages over the timber frame. First, the metal joints of the frame were more resistant than timber joints to the shock and vibrations caused by firing the weapon.37 Second, a metal frame is not subject to variations of humidity. Such variations may cause a timber frame to twist and crack, rendering the weapon useless. Third, the metal frame gave the opportunity to use replaceable field-frames. As the reconstruction of the cheiroballistra (FIG. 11) shows, there is no difficulty in drawing the field-frame from the forked ends of the two transverse struts. As the Orgova find proves, there were holes in the forked ends of the arched strut, presumably for holding retaining-pins. To remove the field-frame, one only had to draw out the retaining-pins. A catapult of this type, provided with complete spare field-frames, including the cord-bundles of the torsion spring, could be re-

paired very quickly if a torsion-spring gave way. Another characteristic of the weapon is the

arched strut. In combination with the wide spacing of the field-frames this provided a useful opening in the framework of the catapult, through which the ancient artilleryman could observe the field and spot his target.37a Perhaps the arch was also necessary in connection with a sighting device, but at present there is no positive proof that sights were used.

Like the Hatra ballista the Orgova catapult was not built following the construction-rules and calibration-formulae laid down in the works describing late Hellenistic artillery.38 So these formulae cannot be applied to the Oryova catapult- components in order to calculate the calibre of the engine. But the inner diameter of the two rings of the field-frame is equal to the diameter of the torsion-spring, which must have filled the ring. The diameter amounts to 7-9 cm. Strange to say, the Ampurias catapult had the same spring-diameter. 39The height of the spring is given by the

3"For instance, C. Cichorius, Die Reliefs der Traianssiiule (I896-i9goo), pl. 47.

"3 Philon, Belopoeica 57 (ed. Marsden, note I) illus- trates the difficulties caused by the use of timber frames.

37a Marsden, op. cit. (note I), 227 f. 38 See note i.

3 Schramm, op. cit. (note 3), 40.

14 DIETWULF BAATZ

height of the field-frame (36 cm) plus the height of the two washers. As the washers are lost, the overall height of the springs of the Or?ova catapult is not known. The frame of the Ampurias catapult was 41-5 cm high, the washers a little less than 4 cm each, giving the torsion-springs a height of 49 cm.40 We may conclude that the power of the Oryova catapult may have been equal to or a little less than that of the Ampurias catapult.41 This was a light arrow-shooter only, but to cock the weapon a windlass was needed. In this respect the Oryova catapult differed from the cheiroballistra, a much smaller weapon not provided with a windlass.

The frame of the Or?ova catapult had completely different proportions from those of the Am- purias catapult or other Hellenistic arrow- shooters, and is much wider but lower than the frames of the older machines. The wide, low frames are also a typical feature of the artillery on Trajan's Column. Similar proportions were already noted above in describing the frame of the Hatra ballista. So the wide, low frames seem to be a characteristic of a number of later ancient artillery-types.

Chronology In comparing the Orgova finds with Heron's Cheiroballistra and the artillery on Trajan's Col- umn one has to bear in mind the chronology of these very different sources. Trajan's Column was erected in 113 to commemorate the Dacian wars. The Column gives the earliest representation of this particular type of artillery.42 The Or?ova finds were deposited at the end of the fourth century, nearly 300 years later. The date and author-

ship of Heron's Cheiroballistra are disputed. Marsden identified the author with the Heron of Alexandria who wrote the Belopoeica probably in the first half of the second century A.D.43 But R. Schneider had already laid stress upon the use of different terms in the Belopoeica and in the Cheiroballistra for the same artillery-component, for instance in describing the claw of the trigger- mechanism.44 This points against the same author having written both technical texts. Schneider also noticed words borrowed from Latin in the Greek text of the Cheiroballistra, for instance the word for 'field-frame' (see above) or the title itself, which is clearly a translation of manuballista.

The Latin word occurs in late Roman texts only.45 Consequently Schneider concluded the Cheiroballistra to be a Byzantine text.46 To the present writer the arguments seem to support Schneider's opinion. If this is right, the artillery- type first represented on Trajan's Column was in use over many centuries well into the Byzantine period. During this long span of time some sort of development and of course many variations are to be expected. One of these variations was the cheiroballistra or manuballista (FIG. 11), a sort of torsion-crossbow. This small weapon was cocked without a windlass in a way similar to Heron's gastraphetes47 and was served, as the name indicates, by one man only.

THE GORNEA FIND

Three iron objects found by N. Gudea in the late Roman fort at Gornea (Roumania) may have been components of such manuballistae. Two of them were discovered in the projecting south-eastern corner-tower, the third in the south-western corner-tower.48 The fort was of the same type as at Or?ova, and the finds here too came from a destruction-layer of the end of the fourth century A.D.

The three objects are of similar type, so only No. 2 is represented here on FIG. 12. Fundamen- tally the construction of the objects is the same as that of the Or?ova field-frame. Consequently the Gornea finds are interpreted as field-frames also. They differ only in being much smaller and

0o Dimensions taken from the drawing in Schramm, op. cit. (note 3), 44, fig. 16, and from Schramm's reconstruction (note 8).

S1 The power may have been equal if the washers of the

Orlova catapult were higher than the Ampurias

washers. The same assumption is made as is expressed in note 21.

42 Marsden, op. cit. (note 7), 188-90. " Marsden, op. cit. (note I), 209-10. ( Schneider, op. cit. (note 33), 164-5. See also the

review of Marsden's book (note I) by A. G. Drachmann in Technology and Culture 13 (1972), 492-3.

4 Vegetius, mil. 2,15; 4,22; Anonymous, de rebus bellicis (ed. R. Schneider, Berlin, 19o8), p. 19; also manuballistarius: Vegetius, mil. 3,14; 4,21.

46 Schneider, op. cit. (note 33), 167-8. 4' Schramm, op. cit. (note 3), 16, fig. 3; 47-9; pl. I);

Marsden, op. cit. (note 7), 5-12. 48 N. Gudea, op. cit. (note 30); id., 'Gornea', Bana-

tica, Studii ?i Cercettln Arheologice (I977), 82-3, Nos. 20-22; figs. 46a, 59. The finds are now preserved in the museum at Repija (Roumania).


FIY. 12. Gornea. Field-frame (Kafi7o-rptov) of manuballista. Scale approx. 1:2.

lighter than the Oryova field-frame. The Gornea field-frame No. 2 had a weight of 426 g after de- rusting. The total height was 14-4 cm. The two rings at the top and bottom had an inner diameter of 5-9 cm and an outer diameter of 8-5 cm. The cross-section of the iron band of the ring was 1.3 by 0-4 cm. Each ring was pierced by four small round holes and by two larger, rectangular holes, the latter being necessary for riveting the two beams to the ring.

The distance between the two beams was 6.9 cm, their cross-section roughly 2.0 by 0.7 cm. One of the beams was curved, and in the curve the cross-section went up to 3-5 by 0.7 cm. The upper, smaller loops fastened to the beams had an inside width of 2-0 by 1-6 cm and the two larger bottom loops 3-1 by 2.0 cm.

Some of the dimensions correspond to those given in Heron's Cheiroballistra. For instance, the distance between the beams is given in the Cheiroballistra as 31 dactyls, equal to 6-5 cm49 (Gornea No. 2: 6.9 cm). Also the cross-sections of the iron beams and rings are comparable. Therefore the dimensions of the Gornea finds may be used the other way round to clear up the question which of two different text-traditions of a dimension of Heron's Cheiroballistra may be

the more probable one. The height of the field- frames is indicated in the text by the length assigned to the two beams. Wescher and Schneider

preferred to accept 10- dactyls (19-4 cm),50 Mars- den followed the other reading of 20 dactyls (37 cm).51 Consequently the reconstruction of the cheiroballistra built by Marsden acquired nearly double the height it would have had if built to the dimension given in the first reading.52 The machine accordingly was much more powerful and needed to be tightened by a windlass, which is not mentioned in the text. Marsden even disregarded the part of the text describing a crescent-shaped timber placed at the end of the case where the

" Heron, Cheiroballistra 128 (ed. Marsden, note I). The conversion of dactyls into cm is based on the assumption that the dactyl of Heron's Cheiroballistra is derived from the Roman uncia: I? dactyls = I uncia, cf. Schneider, op. cit. (note 33), I65, n. 2; Mars- den, op. cit. (note I), 200, n. 21; 228. If one Roman foot equilk 29-6 cm and 12 unciae go to the foot, one dactyl is equal to I185 cm.

So Wescher, op. cit. (note I), 128, n. 5; Schneider, op. cit. (note 33), 154, n. 2.

.1Marsden, op. cit. (note I), 222 f., n. 17.

"2 Marsden, op. cit. (note I), 224, fig. 9; 232-3; pl. 6-8.

16 DIETWULF BAATZ

windlass is mounted in bigger catapults.53 But another weapon of antiquity, which had some similarity with a mediaeval cross-bow, namely Heron's gastraphetes, was also provided with such a crescent-shaped timber to enable one man to tighten the machine without a windlass.54 The height of the Gornea field-frame No. 2 at 14.4 cm gives the lower number of 101 dactyls the greater probability, and leads to a different reconstruction (FIG. I I).55

But the differences between the field-frames of Heron's Cheiroballistra and those at Gornea should not be overlooked. The Gornea field- frames had for instance much larger loops fastened to the beams. The size of the loops points to the possibility of timber traverses being employed to hold the field-frames in position instead of the iron struts of Heron's Cheiroballistra. This may explain why only the field-frames were found at Gornea. Clearly a variety of types of manuballistae existed.

Conclusion

Nearly all research on ancient artillery has been concerned with the main written technical sources (Philon, Heron and Vitruvius). The most devel oped artillery-pieces described by these sources reflect the state of technique reached in late Hel- lenistic times. The Roman army had introduced artillery as early as in the third century B.C. Over the following centurie3 up to the late Republic the Romans remained dependent upon the technical skill of Greek engineers. Not long after the Roman army became the only outstanding mili- tary power of the Old World the necessity of having its own independent artillery-production must have been felt. This is reflected by the career of Vitruvius56 and the chapter on artillery which he wrote. The text of Vitruvius includes what are perhaps the first Roman innovations in artillery.57 As has been noted by Marsden, the last representation of the Hellenistic type of two- armed torsion-artillery is to be found on the tombstone of Vedennius, which can be dated to the end of the first century A.D.58 Only a few years later, during Trajan's Dacian wars, a completely new development of arrow-shooting artillery is seen in action (PL. IV B).

The new finds illustrate some of the artillery types in use after this important Roman develop-

ment in ancient artillery. All new finds show in- fluences from the type of arrow-shooter represented on Trajan's Column. In spite of all differences of construction the Hatra ballista (third century) and the Orjova arrow-shooter (fourth century) both, for instance, had very low but wide frames, in contrast to the narrow high frames of the Hellenistic torsion-engines. The new type of artillery had probably already been developed in the second half of the first century A.D. and la3ted for centuries well into the Byzantine period. Only few indications of these weapons are to be found in contemporary written sources, the most important being Heron's Cheiroballistra, a late Roman or Byzantine text.59

"3 Heron, Cheiroballistra 124 (ed. Marsden, see note I); A. G. Drachmann, Technology and Culture 13 (1972), 493.

"5 Heron, Be!opoeica 77-8 (ed. Marsden, note I). See also note 47.

"J In reconstructing the cheiroballistra some points remain undecided. The text does not tell us how to assemble the components of the weapon. The two field- frames differ in that one is the mirror-image of the other (FIG. IO,I). As we do not know which of the frames is to fit which side of the weapon, there are eight possibilities for mounting each field-frame on the forked ends of the transverse struts. Some of them may be ruled out, because the curves in the beams of the field-frames were certainly intended to accommodate the arms of the machine. Another difficulty is connected with the inner diameter of the washers. The text gives an extremely small figure (I- dactyls, equal to 2.5 cm), which is disputed by Marsden, op. cit. (note I), 224 f., n. 20.

" Vitruvius I praef. 2; RE IX A,I, 420-89; Marsden, op. cit. (note I), 3-4.

"7 The hole in the washer of Vitruvius's ballista is not circular as in the older machines but oval, allow- ing more spring-cord to be placed in the torsion- springs. Furthermore the stone-thrower of Vitruvius may have been stronger than a stone-thrower of the same size built after Philon's instructions, cf. Marsden, op. cit. (note I), 197-200, n. 21. Marsden's proposal to read the dimensions of Vitruvius's ballista in unciae and not in digiti as given in the text is hard to accept, because this seriously interferes with the text.

"s Marsden, op. cit. (note 7), 185; 190, n. 2; pl. I. " The date of Heron's Cheiroballistra is discussed

above in the section on chronology CD. 14). Other late sources also seem to refer to the type of artillery having an all-metal frame and especially the arched strut mentioned in Heron's Cheiroballistra, cf. Marsden, op. cit. (note I), 247, n. 2.

Saalburg-Kastell, D-638 Bad Homburg 1, West Germany


ACKNOWLEDGEMENTS

First I have to thank Nicolae Gudea of the Insti- tutul de Istorie gi Arheologie, Cluj-Napoca (Rou- mania), who sent photos and drawings of the Orgova and Gornea finds and invited me to study the objects at Cluj. The investigation of the Hatra ballista was only made possible by the generous invitation extended to me by Isa Salman, Director- General of Antiquities, Baghdad (Iraq). My thanks are also due to W. I. Al-Salihi of the Directorate- General of Antiquities, Baghdad, the excavator of the ballista, for giving all necessary information and

providing the photos PL. II A, III A. Without sub- stantial financial aid given by the Deutsche For- schungsgemeinschaft, Bonn-Bad Godesberg (Ger- many) I could not have accomplished the journeys necessary for investigating the finds. Very helpful and clarifying was the correspondence I had with the late E. W. Marsden (then at Liverpool), who was very enthusiastic over the Roumanian finds, with M. Hassall (London) and with G. Drachmann (Lyngby, Denmark), whom I have to thank for his critical comments and valuable suggestions.

PLATE I

(Photo: D. Baatz)

A. Hatra (p. 3). Main line of defences with tower Andrae xIx near the North Gate seen from the town side (from SE). The find-spot of the ballista is indicated by an arrow. The photo was

taken in December 1975.

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B. Hatra. Reconstruction of the North Gate and adjacent defences seen from NW. To extreme right: Tower Andrae xix having on top two ballistae. (After W. Andrae, 1912, fig. 26: see p. 4.

note I I.)

PLATE II

41

4

r.r

(Photo: W. 1.Al Salihi, Direct orate-G eneral of Antiquities, Baghdad)

A. Hatra. Frame of ballista as found behind the town-wall. Seen from the North, from the top of the main town-wall (p. 4).

(Photo: D. Baatz)

B. Orsova. Arched strut (Kaca&ptov) of catapult (pp. 11-12). Scale approximately 1: 12.

PLATE III

(Photo: W. I. Al-Salihi, Directorate-General of Antiquities, Baghdad)

A. Hatra. Iron lever, bronze washer and bronze counter-plate of ballista during excavation (p. 4).

(Photo: D. Baatz)

B. Hatra ballista. Bronze washer resting on counter-plate (after cleaning) (p. 5).

PLATE IV

(Photo: D. Baatz)

A. Hatra ballista. Bronze corner-fittings mounted on reconstructed timber frame (p. 4).

(Photo: Saalburgmuseum)

B. Trajan's Column, Rome. Two arrow-shooers mounted on carriages (after a plaster cast) (p. i6).

PLATE V

(Photo: D. Baatz)

A. Orsova. Field-frame (Kagct iE-rpttov) of catapult. Below: the bottom ring seen from the under side (p. 9). Scale approximately I: 3-5.

Documents

BaatzArtillery