07-23-2009, 07:58 AM
The artillery crowd has been too quiet of late, so here's a little something to get you talking and thinking. :twisted:
With all the controversy about different types of bases, winches, and in-swingers versus out-swingers I decided to take a closer look at one of the points where nearly all the experts and re-constructionists agree. One common feature of nearly every design is the “slider”. Everyone knows that it’s supposed to be a long board with a groove in the top for the bolt and a trigger on a raised block at the rear. The whole assembly rides in a dovetail joint in the case. We know this is correct for the gastraphetes because Heron said so quite explicitly. The small gastraphetes is a belly-cocker so its slider is used to draw the bow. Heron’s cheiroballista is essentially a gastraphetes with a different power source and as one might expect, their triggers, cases, and dovetailed sliders are quite similar. What do the sources have to say about the slider in the context of larger stand- mounted and winch-spanned scorpions? (note: all translations are from Marsden’s “Greek and Roman Artillery: Technical Treatises”
For the earliest large straight-spring engine Ctesibius'(via Heron) description is consistent with the smaller machine including the case, block, slider, and dovetails.
Biton’s work is more difficult to follow and he doesn’t mention the block, but the grooved slider riding in the hollow case is present. Both Ctesibius and Biton mention the use of ropes and pulleys on the largest engines to draw the slider forward to reach the bowstring.
Philon lists the case and indicates its proper length. He does not mention the slider. The first mention of the stock and related components is found in his discussion of the “wedge” engine…
We make the case, mounting, block, windlass, and hand-spikes like the standard ones, that is to say, the old ones, except that we slightly increase the size of the pull-back system.
Philon 61. 30-31
The question of the case, mounting, and the block, has been dealt with, because you must simply use the same old type…
Philon 62. 25-26
The mounting, case, block, claw (which draws the bowstring), the windlass, ratchet, hand-spikes, and all other parts in this machine, are constructed exactly as in other arrow-firers…
Philon 68. 4-5
This indicates that there is a standard configuration and that it incorporates a block. Much more extensive coverage is given to Dionysius’ repeating catapult,
“…which has a unique and very intricate arrangement.”
Philon 63. 21
In his introduction to the repeater he continues using the term block.
Quite a lot of missiles were loaded all at the same time into the case, and whenever the block was pulled forward, the claw jumped over the bowstring of its own accord, gripped it, and was automatically secured by the trigger.
Philon 73. 27-28
It is only when he elaborates on the engine’s unique features, that the term slider is introduced.
The case’s length conformed to the usual; but its thickness was 6 dactyls, its breadth 5 dactyls, and depth 3 dactyls. It had on it a wooden structure of appropriate breadth and height, which covered the whole case, but was just a little longer than the distance over which the bowstring was to be pulled back. This structure was made as a slider so that it could be pushed through the case. On this slider was fitted a bronze claw, made with a double prong. It was so contrived that, automatically, it first grasped the bowstring and locked the trigger and, then, when drawn back, released the trigger, all in the following way.
The claw was fitted to the slider, just as to the blocks in other catapults, except that it was low down, while the locking trigger projected a little at one side (as usual), but did not project at all on the other. When the bowstring had to be pulled back, the slider was in the forward projecting position and the excess part of it was pushed out at the front through the frame…But, when the roller revolved and the recess pointed downwards, the missile fell out of it onto the slider which had in it a shallow channel like a groove.
Philon 74.
If sliders were still the rule and not the exception in regards to stand-mounted torsion arrow-shooters in Philon’s time, why would he have gone to such length describing its shape? Couldn’t have just said it’s wider and has no raised block? Why mention that it can be pushed through the case, wouldn’t that be expected? Likewise, if all other “normal” engines had sliders would the projection of the slider through the frame be noteworthy? If, on the other hand, we allow that most engines of this era could have had some other design, then such an elaborate description is warranted. In the passage he gives a measurement for the depth of the slot in which the slider travels, but makes no mention of the dovetails associated with other slider weapons like the gastraphetes. Pushed forward without them, a slider would cantilever downwards out of the case. Perhaps in this instance having an upper case to hold the slider in place made dovetails unnecessary, but if they were a standard feature one would expect an explanation of their omission.
Vitruvius makes no mention of any dovetails when discussing the case, for which he includes its Greek nomenclature. We know he is familiar with the concept of dovetails because he uses them to hold the winch box together. When he discusses canalis fundus (the base of the groove) diostra, the Greek term for “slider”, is not included and again there is no mention of any dovetails. If they were needed to keep the "slider" from falling out he'd probably have mentioned them. Another issue raised by his description of the canalis fundus is its width. He gives a measurement of 1/4f, which correlates exactly with the 1/4f aperture he leaves in the center stanchion. To accommodate a wider dovetail, most reconstructionists carve out space for it in the bottom half of the aperture or simply widen out the whole opening to fit their theory. Neither solution quite fits Vitruvius' text. The term he uses for the block, chelonium, also appears in his description of the base where it refers to a hollow block or "shell". The chelonium and trigger are described in the same sentence, but not with the so called "slider", of which it is supposedly a part. To me, this indicates that the block, containing the claw and trigger, was more likely a separate item riding as a shuttle on top of a fixed rail called the base of the groove. John Anstee proposed a similar solution called a “trigger unit” on his carroballista.
No further mention is made of dovetails or sliders until Heron's cheiroballistra which has neither winch nor mounting, but like its ancestor the gastraphetes includes a crescent shaped fitting at the end of the case. This indicates that it too was belly-cocker which would need a dovetailed slider to function. On winch-drawn weapons there is no compelling reason for the “slider” to move at all. If such a fixed rail weapon were configured as an iron-framed in-swinger, with the frame mounted halfway along the case, the forward half of the case could be eliminated leaving only the canalis fundus projecting forward. Perhaps this is what Ammianus had in mind when he spoke of the quadratis stylus. It does help explain why the engines on Trajan’s Column appear to have their “sliders” forward all the time.
The existence of “sliders” on Roman era stand-mounted arrow shooters is therefore more an assumption rather than an established fact. There are two sources which make this assumption appear reasonable. First, the concept is carried forward from the very earliest descriptions by Ctsebius (Via Heron) and Biton. The pulling-forward mechanisms they associated with sliders are not generally mentioned by later writers. The only instance is the polyobolos which Philon describes as unique, having both a slider and a system for pulling it forward. Since this weapon is the exception rather than the rule, it is possible that a simple solution such as only moving the block had been arrived at and was in common use by Roman times. The other source, from which the slider and dovetails are borrowed, is the cheiroballistra. Using the designs of hand-held belly-cocked weapons like the gastraphetes or cheiroballistra to “fill in” perceived gaps in larger weapons is like using the manual for a rifle to assemble a howitzer. Just because two systems perform similar functions, it doesn’t mean they function the same way. Once a weapon becomes powerful enough to require a winch there is no longer any reason for the whole slider to move.
For those who find my latest heresy preposterous I refer you to the Cupid Gem which shows Cupid using a two-lever ratcheted winch to span a torsion catapult. According to the position of the claw and bowstring the arms are only partly drawn back, yet there is no portion of the "slider" visible beyond the face of the frame. If you can offer a better explanation than the fixed-slider/sliding-block hypothesis, that doesn’t include the tired phrase “the artist was wrong”, I’d love to hear it.
With all the controversy about different types of bases, winches, and in-swingers versus out-swingers I decided to take a closer look at one of the points where nearly all the experts and re-constructionists agree. One common feature of nearly every design is the “slider”. Everyone knows that it’s supposed to be a long board with a groove in the top for the bolt and a trigger on a raised block at the rear. The whole assembly rides in a dovetail joint in the case. We know this is correct for the gastraphetes because Heron said so quite explicitly. The small gastraphetes is a belly-cocker so its slider is used to draw the bow. Heron’s cheiroballista is essentially a gastraphetes with a different power source and as one might expect, their triggers, cases, and dovetailed sliders are quite similar. What do the sources have to say about the slider in the context of larger stand- mounted and winch-spanned scorpions? (note: all translations are from Marsden’s “Greek and Roman Artillery: Technical Treatises”
For the earliest large straight-spring engine Ctesibius'(via Heron) description is consistent with the smaller machine including the case, block, slider, and dovetails.
Biton’s work is more difficult to follow and he doesn’t mention the block, but the grooved slider riding in the hollow case is present. Both Ctesibius and Biton mention the use of ropes and pulleys on the largest engines to draw the slider forward to reach the bowstring.
Philon lists the case and indicates its proper length. He does not mention the slider. The first mention of the stock and related components is found in his discussion of the “wedge” engine…
We make the case, mounting, block, windlass, and hand-spikes like the standard ones, that is to say, the old ones, except that we slightly increase the size of the pull-back system.
Philon 61. 30-31
The question of the case, mounting, and the block, has been dealt with, because you must simply use the same old type…
Philon 62. 25-26
The mounting, case, block, claw (which draws the bowstring), the windlass, ratchet, hand-spikes, and all other parts in this machine, are constructed exactly as in other arrow-firers…
Philon 68. 4-5
This indicates that there is a standard configuration and that it incorporates a block. Much more extensive coverage is given to Dionysius’ repeating catapult,
“…which has a unique and very intricate arrangement.”
Philon 63. 21
In his introduction to the repeater he continues using the term block.
Quite a lot of missiles were loaded all at the same time into the case, and whenever the block was pulled forward, the claw jumped over the bowstring of its own accord, gripped it, and was automatically secured by the trigger.
Philon 73. 27-28
It is only when he elaborates on the engine’s unique features, that the term slider is introduced.
The case’s length conformed to the usual; but its thickness was 6 dactyls, its breadth 5 dactyls, and depth 3 dactyls. It had on it a wooden structure of appropriate breadth and height, which covered the whole case, but was just a little longer than the distance over which the bowstring was to be pulled back. This structure was made as a slider so that it could be pushed through the case. On this slider was fitted a bronze claw, made with a double prong. It was so contrived that, automatically, it first grasped the bowstring and locked the trigger and, then, when drawn back, released the trigger, all in the following way.
The claw was fitted to the slider, just as to the blocks in other catapults, except that it was low down, while the locking trigger projected a little at one side (as usual), but did not project at all on the other. When the bowstring had to be pulled back, the slider was in the forward projecting position and the excess part of it was pushed out at the front through the frame…But, when the roller revolved and the recess pointed downwards, the missile fell out of it onto the slider which had in it a shallow channel like a groove.
Philon 74.
If sliders were still the rule and not the exception in regards to stand-mounted torsion arrow-shooters in Philon’s time, why would he have gone to such length describing its shape? Couldn’t have just said it’s wider and has no raised block? Why mention that it can be pushed through the case, wouldn’t that be expected? Likewise, if all other “normal” engines had sliders would the projection of the slider through the frame be noteworthy? If, on the other hand, we allow that most engines of this era could have had some other design, then such an elaborate description is warranted. In the passage he gives a measurement for the depth of the slot in which the slider travels, but makes no mention of the dovetails associated with other slider weapons like the gastraphetes. Pushed forward without them, a slider would cantilever downwards out of the case. Perhaps in this instance having an upper case to hold the slider in place made dovetails unnecessary, but if they were a standard feature one would expect an explanation of their omission.
Vitruvius makes no mention of any dovetails when discussing the case, for which he includes its Greek nomenclature. We know he is familiar with the concept of dovetails because he uses them to hold the winch box together. When he discusses canalis fundus (the base of the groove) diostra, the Greek term for “slider”, is not included and again there is no mention of any dovetails. If they were needed to keep the "slider" from falling out he'd probably have mentioned them. Another issue raised by his description of the canalis fundus is its width. He gives a measurement of 1/4f, which correlates exactly with the 1/4f aperture he leaves in the center stanchion. To accommodate a wider dovetail, most reconstructionists carve out space for it in the bottom half of the aperture or simply widen out the whole opening to fit their theory. Neither solution quite fits Vitruvius' text. The term he uses for the block, chelonium, also appears in his description of the base where it refers to a hollow block or "shell". The chelonium and trigger are described in the same sentence, but not with the so called "slider", of which it is supposedly a part. To me, this indicates that the block, containing the claw and trigger, was more likely a separate item riding as a shuttle on top of a fixed rail called the base of the groove. John Anstee proposed a similar solution called a “trigger unit” on his carroballista.
No further mention is made of dovetails or sliders until Heron's cheiroballistra which has neither winch nor mounting, but like its ancestor the gastraphetes includes a crescent shaped fitting at the end of the case. This indicates that it too was belly-cocker which would need a dovetailed slider to function. On winch-drawn weapons there is no compelling reason for the “slider” to move at all. If such a fixed rail weapon were configured as an iron-framed in-swinger, with the frame mounted halfway along the case, the forward half of the case could be eliminated leaving only the canalis fundus projecting forward. Perhaps this is what Ammianus had in mind when he spoke of the quadratis stylus. It does help explain why the engines on Trajan’s Column appear to have their “sliders” forward all the time.
The existence of “sliders” on Roman era stand-mounted arrow shooters is therefore more an assumption rather than an established fact. There are two sources which make this assumption appear reasonable. First, the concept is carried forward from the very earliest descriptions by Ctsebius (Via Heron) and Biton. The pulling-forward mechanisms they associated with sliders are not generally mentioned by later writers. The only instance is the polyobolos which Philon describes as unique, having both a slider and a system for pulling it forward. Since this weapon is the exception rather than the rule, it is possible that a simple solution such as only moving the block had been arrived at and was in common use by Roman times. The other source, from which the slider and dovetails are borrowed, is the cheiroballistra. Using the designs of hand-held belly-cocked weapons like the gastraphetes or cheiroballistra to “fill in” perceived gaps in larger weapons is like using the manual for a rifle to assemble a howitzer. Just because two systems perform similar functions, it doesn’t mean they function the same way. Once a weapon becomes powerful enough to require a winch there is no longer any reason for the whole slider to move.
For those who find my latest heresy preposterous I refer you to the Cupid Gem which shows Cupid using a two-lever ratcheted winch to span a torsion catapult. According to the position of the claw and bowstring the arms are only partly drawn back, yet there is no portion of the "slider" visible beyond the face of the frame. If you can offer a better explanation than the fixed-slider/sliding-block hypothesis, that doesn’t include the tired phrase “the artist was wrong”, I’d love to hear it.
P. Clodius Secundus (Randi Richert), Legio III Cyrenaica
"Caesar\'s Conquerors"
"Caesar\'s Conquerors"
