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Énergie hydraulique et machines élévatrices d'eau dans l'Antiquité

 | 
Jean-Pierre Brun
, 
Jean-Luc Fiches

Scies hydrauliques

A stone relief of a water-powered stone saw at Hierapolis, Phrygia

A first consideration and reconstruction attempt

Klaus Grewe et Paul Kessener

Texte intégral

  • 1 First published in: F. D’Andria, M. P. Caggia, Hierapolis di Frigia I. Le attività della Missione (...)

1Not many drawings or images of technical constructions or machinery have been preserved from classical times1. Only in few cases is has been possible to reconstruct the functioning of a technical contraption by means of a description or illustration of the ancient engineer/designer, both for large constructions and for manual tools alike.

  • 2 A skilful engineer of our times may, from the construction itself, be able to know what remains in (...)

2The modern engineer has no choice but to extract data from the often limited and incomplete remains of the ancient construction or apparatus to decipher the code or plan of the design. This led Th. Mommsen, when confronted with an inscription on the funerary monument for Nonius Datus, describing the construction of a tunnel for the aqueduct at Saldae (Algeria), to delegate this problem, as he writes: « es wird vielleicht ein verstandiger Ingenieur unserer Epoche aus dem Bauwerk selbst dasjenige zu lösen wissen, was uns im Bericht seines romischen Vorfahren unverständlich bleibt »2.

  • 3 Ritti 2006.

3In the necropolis west of Hierapolis, to the left and to the right of the road towards the’Frontinus Gate’, the numerous tombs and sarcophagi are equipped with countless inscriptions and, fewer in number, with a relief. One relief, on one end of the stone cover of a sarcophagus, shows a technical contraption. Together with an inscription a water-powered twin stone saw is depicted, in schematic outline. From the inscription it is understood that the sarcophagus was dedicated to a certain M. Aurelios Ammianos. It is dated second half or end of 3rd c. AD3.

  • 4 A report by Fritz Mangartz of the Osterreiches Archâologisches Institut ÖAI on the Ephesos stone s (...)

4The Hierapolis relief shows important new information about technicalities involved in the mechanism of the water powered saw mill, which requires the conversion of rotary motion into linear motion. Undisputed remains of water-powered stone saw mills exist at Ephesos (6th / early 7th c. AD) and, from recent findings by Jacques Seigne, at Gerasa, Jordan (6th c. AD). In this paper the Hierapolis relief is discussed, in view of the findings at Gerasa and Ephesos4.

The Hierapolis relief (Fig. 1-4)

5On the relief one’s attention is drawn to the large vertical wheel on the right having a long horizontal shaft extending to the left. To the right of the wheel a chute is depicted in the form of some kind of inclined piping or channel, aiming at half height of the wheel, suggesting that the wheel was driven by waterpower and employed as a breast wheel. The impact of the water onto the blades drives the wheel and would guarantee a constant rotational movement, whereby the energy needed to operate the saw is generated.

Fig. 1. The Hierapolis relief: cover of the sarcophagus of M. Aurelios Ammianos with water-powered twin stone saw and inscription (photo K. Grewe)

Fig. 2. The Hierapolis relief (detail): Water wheel and chute, water from chute aiming at half height of water wheel (photo K. Grewe).

6The transfer of the rotation of the waterwheel to the stone saw mechanism has been depicted schematically. The shaft of the water wheel appears to be equipped with a gear train of two gears, one wheel mounted onto the shaft of the big wheel. This wheel drives a third wheel, apparently equipped with cranks or with crank wheels (a disk of some material fixed onto the wheel shaft and equipped with a wooden or metal eccentric pin), and connecting rods to convert the rotational movement of the wheel into a linear one, needed to operate the saws.

Fig. 3. The Hierapolis relief (detail): gear train, conversion of rotation into reciprocal linear movement (photo K. Grewe)

7Both stone saws are depicted in sufficient detail to conclude that they are representing so called span-saws, the saw blades kept in tension by means of a (wooden) frame. The image shows the saws while operating, the blades having progressed half-way through the stone blocks.

8Although the saws have been depicted correctly, a mechanism to guide the saw blades is not present. A smooth and regular saw-cut can only be achieved when the blades are kept in vertical position and movement sidelong is prevented. To this purpose a guiding frame in envisaged in which the saw, apart from the reciprocal movement by the connecting rods, may move only in strict downward direction. As in modern stone saws, several parallel saw blades may be mounted next to each other, allowing several stone slabs to be cut simultaneously. Figure 4 shows a reconstruction drawing of the stone saw of the Hierapolis relief, with a crank wheel with eccentric pin and with a crank (on either side of the shaft of the third wheel), and with a simple guiding mechanism for one of the saws.

Fig. 4. Reconstruction of the relief (drawing P. Kessener)

  • 5 Wikander 2000, p. 402.
  • 6 Lewis 1997, Wikander 2000, p. 406-7.
  • 7 Schiøler 2005, p. 34.

9The conversion of rotary movement into a linear one is one of the most controversial issues in the study of ancient applications of waterpower5. One method that is ascertained is the cam or camshaft to drive tilt-hammers or trip-hammers. Cams go back to the 3rd C BC in Greek automata, and cam-operated tilt hammers are thought to have been used in the Roman Empire6. A waterwheel moving a saw, however, requires a crank or crank wheel and a connecting rod. According to Schiøler, all historians of technology agree that the one-armed crank was unknown in Roman times’7. The Hierapolis relief obviously proves differently.

The stone saw mills at Ephesos and at Gerasa

10The mill at Gerasa and the one at Ephesos show several similarities. Each mill is located in a rectangular workshop, one of the walls equipped with a headrace some 3-4 m above floor level, millrace and tailrace in the floor of the shop. At Gerasa the positions for the bearings, to accommodate the shaft of a waterwheel, have been preserved in the millrace walls. Seigne estimated that the remains suggest a vertical overshot waterwheel about 50 cm wide having a diameter of 4-4.5 m. The outer surface of the mill race walls show circular wear marks showing that something was fixed at either end of the wheel shaft rotating with the wheel. Seigne stated that a wooden disk of at least 1 m in diameter was fixed to the wheel shaft rotating with the water wheel.

11In the workshop at Ephesos as well as at Gerasa two large stone blocs have been found which are partly cut into slabs. At Ephesos the blocs are rectangular and some 2. 2m long. They are still in their original position, parallel to each other on either side of the mill race. The blocs at Gerasa consist of limestone drums 1. 51 and 1. 67 m. long and about 1 m. in diameter, their original position are thought to be parallel to each other left and right to the mill race as well. The Ephesos blocs show 2 parallel saw-cuts, the Gerasa drums show 4 grooves each, penetrating to the same depth even though the outer surface is curved. Evidently the saws worked on both blocs simultaneously, with parallel blades for each block.

  • 8 The notion that the crank was unknown in Roman times led Schiøler to the reconstruction of the Eph (...)
  • 9 To the opinion of Niall Roberts, who translated Seigne’s originally French article (Seigne J. 2002 (...)

12In the reconstruction of Schiøler the waterwheel is envisaged to drive a large horizontal frame in which two sets of saw blades were fixed. The weight of the heavy rectangular frame, which is to be guided on its way down to prevent deviation from vertical, is thought to be compensated by counterweights exerting an upward force by means of ropes over pulleys8. Seigne, however, envisages two separate vertical saw frames, as in the Hierapolis relief, one for each stone bloc, moved to and fro by connecting rods that are driven by wooden disks equipped with a metal pin and fixed to the shaft of the water wheel (crank wheels)9. As the frames are smaller and less heavy than the horizontal frame in Schiøler s reconstruction no compensatory weights would be necessary.

The Hierapolis relief and the mills at Ephesos and at Gerasa

  • 10 Breast wheels are thought to have been invented as a compromise between overshot and undershot whe (...)
  • 11 Gerasa: 6th c. AD, Seigne 2002, p. 16, Ephesos: 6th or early 7th c. AD, Schiøler 2005, p. 34. Wika (...)

13In the Hierapolis relief the waterwheel appears to be applied as a breast wheel, the sloping chute pointing to the wheel at half height10. Two blocs are sawn simultaneously, by two span-saws, the saw blades fitted into vertical frames. Such frames may accommodate two or more parallel saw blades. Thus, from the Hierapolis relief, a reconstruction of the stone saw mills at Ephesos and at Gerasa11, with crank wheels or cranks and connecting rods, and with vertical saw frames, appears realistic.

14According to Ritti, the relief and the inscription must be dated to the 2nd half or end of the 3rd c. AC, preceding the attested Ausonius poem on the marble saw mills at the Ruwer (371 AD) a hundred years, and three centuries before the mills at Ephesos and at Gerasa. Ritti states that the inscription tells us that M. Aurelius Ammanius is referred to as an ingenious and inventive man (δαιδάλεος), not just a labourer or an official, a man who maybe invented this type of stone saw or introduced some new element to the saw mechanism.

15The Hierapolis relief shows us beyond doubt that vertical saw frames have been applied for water-powered stone saws, and, of great importance, that the crank wheel /crank was known in the 3rd c. AD. There are, however, remarkable differences between the situation at Ephesos and Gerasa and the one depicted on the Hierapolis relief. At Gerasa and apparently also at Ephesos, the shaft of the water wheel is short, not much longer than needed for the wheel itself and the two bearings on either side of the wheel. In the Hierapolis relief the water wheel’s shaft is extended, long enough to accommodate a smaller, toothed wheel that serves as a driver for a third wheel, to the shaft of which the crank wheels are mounted. This gear train reminds of the machinery of vertical water mills applied for driving millstones, the Vitruvian mill, where a vertical cogwheel is mounted onto the shaft of the water wheel, driving a horizontal wheel to which the rotating millstone is fixed. The cogwheel and the horizontal wheel were usually accommodated in a separate space into which the shaft of the water wheel extended, the shaft’s total length usually being between 2.9 and 3.6 m.

Fig. 5. Stone-saw in the grinding mill in Schwerin (Schweriner Schleifmühle) ; (photo P. Schmidt)

16Furthermore, in the Hierapolis relief the saw frames and the stone blocs that are sawn are positioned to the left and to the right from the gear train. This contrasts the situation at Ephesos/ Gerasa, where the blocs are positioned next to each other on one side of the water wheel. The arrangement at Ephesos/Gerasa, the water wheel being positioned next to the wall with the headrace, does not allow an alternative set-up. Maybe it was the artist’s impression, in the Hierapolis relief, to depict the saws and the stone blocs on either side of the driving wheel, but the configuration with the gear train no doubt allows the positioning of the saws in the relief. It may have been the merit of M. Aurelios Ammianos that he changed the combination of vertical cogwheel and horizontal wheel into a gear train with two vertical wheels for the purpose of driving some non-rotational machinery. He may actually have used an existing water mill to experiment, as the only thing he had to do was to replace the horizontal wheel of this gear train by a vertical one and position it below the cogwheel, adding crank wheels, connecting rods and span-saws. This would explain the long shaft of the water wheel and the two extra wheels in the Hierapolis relief.

17By the gear train that Ammianos applied for driving his saws, energy is inevitably lost by friction. One may envisage that, at a later stage, the gear train was abolished to the favour of crank wheels mounted directly onto the water wheel’s shaft, thus simplifying the design, reducing the length of the shaft, and enhancing efficiency of the mill. This would lead to the mill configurations known from Ephesos and Gerasa. One may only speculate that Ammianos was the inventor of the crank or crank wheel, to convert a rotational movement into a linear one, and, that he also was the inventor of the water-powered stone saw. It would have been a revolutionary and tremendous invention. The Hierapolis relief shows us that, whatever the case may be, Ammianos, and the Romans, knew and applied this technique, in his time, the second half of the3rd c. AD.

Bibliographie

Bibliography

Grewe and Kessener 2006 : GREWE K., KESSENER A stone relief of a water-powered stone saw at Hierapolis, Phrygia-a first consideration and reconstruction attempt, in : F. D’Andria, M. P. Caggia, Hierapolis di Frigia I: Le attività della Missione Archeologica Italiana a Hierapolis. Campagne 2000-2003. Atti del Convegno di Cavallino (Le), Convento dei Domenicani, Lecce 9-10 Iuglio 2004. Lecce 2006.

Landels 1978 : LANDELS J. G., Engineering in the ancient world, Los Angeles, 1978.

Lewis 1997 : LEWIS M. J. T., Millstone and hammer. The origins of water power, Hull, 1997.

Mangartz 2006 : MANGARTZ F., Zur Rekonstruktion der wassergetriebenen byzantinischen Stensägemaschine von Ephesus, Türkei, Archäologisches Korrespondenzblatt 36, Heft 4, 2006, p. 573-590.

Reynolds 1983 : REYNOLDS T. S., Stronger than a hundred men, a History of the Water Wheel, Baltimore / London, 1983.

Ritti 2006 : RITTI T., Stridentesque trahens per levia marmora serras: lo schema di un congegno idraulico per segare blocchi di pietra, rappresentato sul sarcofago di M. Aurelios Ammianos di Hierapolis, in : F. D’Andria, M. P. Caggia, Hierapolis di Frigia I. Le attività della Missione Archeologica Italiana a Hierapolis. Campagne 2000-2003. Atti del Convegno di Cavallino (Le), Lecce 9-10 luglio 2004. Lecce, 2006.

Schiøler 2005 : SCHIØLER Th., How to saw marble, J. Int. Molinology 70, p. 34-35.

Seigne 2002 : SEIGNE J., Sixth-Century Waterpowered Sawmill, J. Int. Molinology 64, p. 14-16.

Seigne 2006 : SEIGNE J., Water-powered Stone Saws in Late Antiquity, in: Cura Aquarum in Ephesos, Proceedings of the 12th Int. Congress on the History of Water Management and Hydraulic Engineering in the Mediterranean Region 2004 (G. Wiplinger ed.), BABesch Supll. 12, Leiden, 2006, p. 383-390.

Warnecke 1997 : WARNECKE H., Die antike Marmorsäge, Das Rheinische Landesmuseum Bonn, Heft 2, 1997, p. 33-38.

Wikander 2000 : WIKANDER Ö., The water-mill/Industrial applications of water-power, in : Handbook of Ancient Water-technology (Ö. Wikander ed.), Leiden, 2000, p. 371-410.

Annexes

Appendix

With the deciphering of the Ammianos Relief, a technique of power-transmission has been detected whose introduction was judged to have taken place much later (Fig. 5-11). It is noticeable that in the Ammianos Relief the power-transmission from the water-wheel to the stone-saw was shown in great detail, whereas a very simplified depiction was chosen for the saw itself. For Ammianos, who refers to himself in the text as a skilled inventor, the construction of this machine was probably his life’s greatest achievement. It obviously mattered to him that this great technical achievement should be preserved for posterity in this depiction. Apparently he did not regard the construction of a simple saw as a special achievement, however he attributed great significance to the invention of his engine.

In Schwerin (Mecklenburg-West Pomerania, Germany) an old grinding-mill complete has been preserved; (its inventory is reconstructed 1983/1985 by a Handbook from 1718). The stone used to build the Schwerin Castle was cut and ground in this mill between 1753 and 1857. Today the mill is a museum. The mill is driven by a water-wheel. The power is transmitted from the water-wheel to the saw via a cog-wheel with a crankshaft and a connecting rod. Technically the power transmission almost exactly corresponds to that of Ammianos’stone-saw from Hierapolis.

The details of the saw-box depicted on the Ammianos Relief are less suitable for a reconstruction. In reconstructing such a saw, it has to be born in mind that the saw-blade has necessarily to be moved both horizontally and vertically in order to obtain an even cut. The Schwerin model fulfils these requirements, so that it seems to be correct to regard it as a reconstruction of Ammianos’saw. If one wanted to produce a 1 : 1 working model of Ammianos’saw, the result would appear the same as the Schwerin saw. This demonstrates that no further development took place in this field between Roman times and the 18th century.

Fig. 6. Reconstruction of an antique stone-saw after the mill in Schwerin: saw-table, substructure of the stone-saw with two sunken rails for the saw-carriage (drawing K. Grewe)

Fig. 7. Reconstruction of the saw-carriage. The saw-carriage is moved back and forth by the connecting rod, which produces the horizontal drive (drawing K. Grewe)

Fig. 8. Reconstruction of the tension-frame with the saw-blade. Small wooden pins are fitted into the guide-rail (groove) of the tension-frame, making the vertical movement of the saw-blade possible (drawing K. Grewe)

Fig. 9. Reconstruction of the saw process. The connecting rod moves the saw-carriage horizontally; at the same time the tension-frame with the saw-blade is pressed down vertically by applied weights and cuts into the marble block (drawing K. Grewe)

Fig. 10. The grinding mill in Schwerin. The saw-blade was without teeth on the cutting edge; the drill-hole in the blade is to enable the saw-blade to be fitted into the tension-frame (photo P. Schmidt)

Fig. 11. The grinding mill in Schwerin. Two saw-blades in action (photo P. Schmidt)

Notes

1 First published in: F. D’Andria, M. P. Caggia, Hierapolis di Frigia I. Le attività della Missione Archeologica Italiana a Hierapolis. Campagne 2000-2003. Atti del Convegno di Cavallino (Le), Lecce 9-10 luglio 2004.

2 A skilful engineer of our times may, from the construction itself, be able to know what remains incomprehensible from the text of his Roman ancestors.

3 Ritti 2006.

4 A report by Fritz Mangartz of the Osterreiches Archâologisches Institut ÖAI on the Ephesos stone saw mill awaits publication (F. Mangartz, Die wassergetriebene byzanti-nische Steinsägemachine von Ephesos, Tiirkei (Vorbericht), Archâologisches Korrespondenzblatt (Mainz), to be published). For a recent attempt to reconstruct the Ephesos mill see Schiøler 2005. For the Gerasa mill see Seigne 2002 and 2006.

5 Wikander 2000, p. 402.

6 Lewis 1997, Wikander 2000, p. 406-7.

7 Schiøler 2005, p. 34.

8 The notion that the crank was unknown in Roman times led Schiøler to the reconstruction of the Ephesos mill in his 2005 publication. Schiøler envisages a "flutter wheel" mounted onto two parallel wooden beams, moving a carriage sliding to and fro over the beams. The carriage on its turn would drive a 5x5 m. wooden frame in which two sets of saw blades are mounted, one for each stone bloc. For a reconstruction with compensation weights see also Warnecke 1997.

9 To the opinion of Niall Roberts, who translated Seigne’s originally French article (Seigne J. 2002, Une scierie mécanique au VP siècle, Archéologia 385, p. 36 ff) for the English publication in the Journal of the International Society of Molinology, the wear marks could just as well have been produced by a crank (Seigne 2002, p. 16).

10 Breast wheels are thought to have been invented as a compromise between overshot and undershot wheels, attempting to combine the actions of weight and impact. When the breast wheel was invented is not certain. Reynolds refers to sources not earlier than medieval (Reynolds p. 287). One cannot be sure that the breast wheel was already known in Roman times. At Hierapolis, the artists impression may be deluding.

11 Gerasa: 6th c. AD, Seigne 2002, p. 16, Ephesos: 6th or early 7th c. AD, Schiøler 2005, p. 34. Wikander states early 7th c. for Ephesos (Wikander 2000, p. 405). On Ausonius, and for a discussion of literary sources on saw mills, see e. g. Ritti 2006, also Wikander 2000, p. 405-6.

Table des illustrations

Légende Fig. 1. The Hierapolis relief: cover of the sarcophagus of M. Aurelios Ammianos with water-powered twin stone saw and inscription (photo K. Grewe)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-1.jpg
Fichier image/jpeg, 2,5M
Légende Fig. 2. The Hierapolis relief (detail): Water wheel and chute, water from chute aiming at half height of water wheel (photo K. Grewe).
URL http://books.openedition.org/pcjb/docannexe/image/440/img-2.jpg
Fichier image/jpeg, 166k
Légende Fig. 3. The Hierapolis relief (detail): gear train, conversion of rotation into reciprocal linear movement (photo K. Grewe)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-3.jpg
Fichier image/jpeg, 1,8M
Légende Fig. 4. Reconstruction of the relief (drawing P. Kessener)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-4.jpg
Fichier image/jpeg, 141k
Légende Fig. 5. Stone-saw in the grinding mill in Schwerin (Schweriner Schleifmühle) ; (photo P. Schmidt)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-5.jpg
Fichier image/jpeg, 400k
Légende Fig. 6. Reconstruction of an antique stone-saw after the mill in Schwerin: saw-table, substructure of the stone-saw with two sunken rails for the saw-carriage (drawing K. Grewe)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-6.jpg
Fichier image/jpeg, 18k
Légende Fig. 7. Reconstruction of the saw-carriage. The saw-carriage is moved back and forth by the connecting rod, which produces the horizontal drive (drawing K. Grewe)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-7.jpg
Fichier image/jpeg, 41k
Légende Fig. 8. Reconstruction of the tension-frame with the saw-blade. Small wooden pins are fitted into the guide-rail (groove) of the tension-frame, making the vertical movement of the saw-blade possible (drawing K. Grewe)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-8.jpg
Fichier image/jpeg, 44k
Légende Fig. 9. Reconstruction of the saw process. The connecting rod moves the saw-carriage horizontally; at the same time the tension-frame with the saw-blade is pressed down vertically by applied weights and cuts into the marble block (drawing K. Grewe)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-9.jpg
Fichier image/jpeg, 51k
Légende Fig. 10. The grinding mill in Schwerin. The saw-blade was without teeth on the cutting edge; the drill-hole in the blade is to enable the saw-blade to be fitted into the tension-frame (photo P. Schmidt)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-10.jpg
Fichier image/jpeg, 152k
Légende Fig. 11. The grinding mill in Schwerin. Two saw-blades in action (photo P. Schmidt)
URL http://books.openedition.org/pcjb/docannexe/image/440/img-11.jpg
Fichier image/jpeg, 159k

© Publications du Centre Jean Bérard, 2007

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