Studies of Ancient Rome

>>>> Hegetor’s Ram - Tortoise <<<<

This machine is the subject of by far the most detailed of Athenaeus's and Vitruvius's descriptions, but there are some doubts and misunderstandings which have inspired a succession of astonishingly varied reconstructions through the years, and several uncertainties remain. Athenaeus and Vitruvius both preserve details of a different ram - tortoise from that described by Diade's ram tortoise and borer. This one apparently devised by an otherwise unknown engineer named Hegetor of Byzantium. In essence Hegetor's machine was a 10m-high tortoise with a central turret, but the reconstruction of this key element is controversial. The sources give a detailed descripton of the ramming beam itself, with rope reinforcement and rawhide covering. It has been suggested that Hegetor worked for Demetrius Poliorcetes, who had a penchant for grandiose machinery, though the connection is more than a little tenuous. The historian Diodorus Siculus records that, that during the siege of Salamis, Demetrius ‘constructed enormous battering rams and two ram-carrying tortoises’, and that, at Rhodes his ram-tortoises were ‘many times larger’ than the ditch-filling tortoises that preceded them. The ramming-beams are said to have been 120 cubits (53.2m) long, the very length that Athenaeus attributes to Hegetor’s battering ram, but the practicality of such a long beam has been questioned.

Athenaeus claims that Hegetor’s 120-cubit ram was rectangular in cross-section, and tapered from a rear-end 2 ft. (59cm) ‘thick’ (by which he must mean the ‘height’ of the beam) and 1 1/4 ft. (37cm) broad to a tip 1 ft by 3/4 ft (36.9cm x 22.2cm). Vitruvius gives a completely different set of dimensions: the length, he says, was 104 ft (30.75m), and the rear end was 1 1/4 ft by 1ft (36.9cm x 29.6cm), tapering to a 1 ft by 3/4 ft (29.6cm x 22.2cm) at the tip. (The anonymous Byzantine muddies the waters by combining Athenaeus’s statement of length, with Vitruvius’s dimensions for the thickness of the beam.)

Shramm believed that a 50m beam would buckle, and the ends would drag on the ground, making the whole contraption unusable. He proposed that Athenaeus’s text should be amended to read 120 ft (35.5m), considerably shorter than 120 cubits, but still some way from Vitruvius’s figure. (The alternative approach adopted by the Greek scholar Sir William Tarn, who postulated that a special short cubit of around 34cm was used in Macedon, takes us even further from Vitruvius.)

A better solution, which actually goes some way towards reconciling the two sources, is to assume that the Greek text of Athenaeus has been corrupted during transmission down through the ages, and that an original statement of ’70’ (hebdomekonta) cubits was miscopied as ’120’ (hekatoneikosi) cubits. A length of 70 cubits (31m) is very close to Vitruvius’s measurement (Precisely how Diodorus came upon the measurement of 120 cubits for Demetrius’s battering rams remains unknown; perhaps both he and Athenaeus drew upon a common source, which had already been corrupted by their day.)

The beam was suspended from a rope cradle high up in the turret, and stabalized by rawhide-covered chains running around a pair of rollers. The ramming beam was capped with an iron tip, like the beak of a warship. Basically, this was a hollow lump of iron, designed to fit over the end of the beam, but was secured by four ten-cubit (4.4m) iron strips which trailed back along the beam like streamers and were nailed into position. (Vitruvius calls these streamers lamminae, which is the usual term for a strip of metal, but Athenaeus calls them ‘iron spirals’, implying that they were wound around and along the beam.) The beam was further reenforced with ropes, using a technique well known in the ancient world for bracing the hulls of ships, and then completely wrapped in rawhide, a necessary protection against fire because it was entirely exposed above the level of the tortoise.

The tortoise itself was similar in size to Diade’s model. Athenaeus gives the dimensions as 42 cubits (18.62m) long and 28 cubits (12.42m) wide. Vetruvius’s version, at 60 ft by 13 ft (17.7m x 3.8m), is obviously wrong, and is usually corrected by emending the manuscript 13 (XIII) to read 42 (XLII); 42ft is the equivalent of 28 cubits, and thus matches the width quoted by Athenaeus. Vitruvius’s length of 60 ft is 3 ft short of Athenaeus’s 42 cubits, but this may be a manuscript error. The machine ran on eight wheels, 4 1/2 cubits (1.99m) high and two cubits (0.88m) thick which according to Vitruvius, comprised three layers, each 1ft thick pegged together with dowels and fastened with iron bands. (Here again, Vitruvius uses the word lamminae.) Unfortunately, as with the other eight-wheeled machine, the helepolis of Epimachus, we are not told the configuration of the wheels, but positioning them four abreast would distribute the massive weight of the machine more evenly. Also a machine built to Athenaeus’s dimensions and following the principles of the ditch-filling tortoise would have rested on an undercarriage some 16 cubits (7.10m) square; consequently, there would not have been space for four-in-line wheels, and they must have been arranged four abreast.

Like the ditch-filling tortoise, the ram-tortoise would have had a hipped roof meeting at the top in a transverse ridge. The whole machine would then be boarded over and covered with a fireproof layer. As with Diade’s ram-tortoise, this style of construction resulted in a ‘middle floor’ (mese stege, or media contabulatio) which caused much confusion amongst those trying to reconstruct the machines. In the case of Hegetor’s tortoise, this second storey had floor space of 16 cubits square (7.10m) and headroom of 8 cubits (3.55m) up to the roof ridge. Athenaeus says that it accommodated an artillery position (belostasia) and Vitruvius explains that scorpions and catapults were located there. Firstly, this contrasts with Diade’s version, where the artillery occupied a third storey turret, rising above the the middle floor; and secondly it implies that there were windows through which the catapults could fire. There seems an altogether more practical arrangement than Diade’s rather fragile and cramped turret.

But even though Hegetor deployed the necessary supporting artillery in the middle floor, he did not entirely dispense with a central turret. According to both Athenaeus and Vitruvius, the working of the ram somehow depended upon a frame, which rose through the middle floor to project some 4m above the roof ridge, and incorporated a crow’s nest at the top.

The potential firepower of the tortoise can be estimated by comparing the middle floor area with the space requirements of small to medium-sized catapults, but both the sloping penthouse construction and the timber uprights of the turret must be taken into account. The first would have limited the usable area to the very middle of the floor, and the second divided this across the middle. The rear was best reserved for ladders, allowing the crew to move about the machine. This would leave enough space in front for three 3-span arrow throwers side-by-side. Positioned roughly 9m above ground level, the catapults would have enjoyed a superior vantage point for targeting the average battlements. The construction of the turret is not explained and so we must resort to conjecture. The sources mention four robust 24 cubit (10.64m) uprights , and another two 30-cubit (13.3m) uprights. The latter pair supported a device consisting of two rollers, sitting side by side. In the words of Vitruvius, ‘ the ropes which held back the ram were fastened around these [rollers]’. However, this is not the ram holder itself (kriodoche, or arietaria machina); that component, as both authors explain lay somewhere in front of the double rollers. In addition, whereas Diade’s battering ram seems to have rested upon the ram holder, Hegetor’s ram was suspended in the middle by a thick hank of ropes.

The German scholar Otto Lendle has devised the most plausible interpretation of this enigmatic structure. The ram-holder, being the suspension point for the ramming beam, would have been centrally located in order to distribute the weight most efficiently, and Lendle fixes it between the four uprights of the turret. At this point there would have been less than 2m clearance above the roof of the tortoise, so the suspension-tackle must have been relatively short, to prevent the ramming beam from snagging on the roof ridge.

It has been conjectured that the ropes running from the rollers were in some way instrumental in altering the height of the ram head, and indeed both Athenaeus and Vitruvius suggest that the enemy wall could be battered up to a height of 70 cubits (31m). This is an extraordinary claim, given that the battering ram was suspended only about 26 cubits (11.5m) above ground. In any case, 70 cubits greatly exceeds the usual range of fortification heights: even operating horizontally, the beam would have been higher than most town walls. Sadly, neither author gives any idea of how the battering ram was operated. The necessary pendulum motion would have required some means of pulling the beam backwards, and there were perhaps several ropes attached to its rear end, to be pulled by hauling crews on the ground. Furthermore, the length of the beam’s suspension would have restricted it to short blows. It is not clear how successful this method would be if the beam were set at any angle other than the horizontal, and it must be admitted that many aspects of Hegetor’s ram-tortoise remain a mystery.

Reference:

Duncan B. Campbell, Brian Delf (Illus..), “Greek and Roman Siege Machinery 399 BC -- AD 363,” New Vanguard-78, (Osprey Pub., 2003)

Respectfully Submitted;

Marcus Audens