Friend of the blog, Randi Richert, has been making the case for sometime now, that only the iron rail should extend beyond the kamarion and field frames. I will let him make the point in his own words as they appear on romanarmytalk.com

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“All of the representations on Trajan’s show a substantial portion of what is presumed to be the stock protruding from front of the weapons below the arch. Many refer to this part as the “slider”. This of course creates a rather large problem for the out-swinger crowd to explain away as this so-called slider is never seen pulled to the rear, even when the weapon is loaded and ready to shoot.

Following the ideas of John Anstee, Firefly’s “slider” is a fixed to the stock and only the block (chelonium)containing the claw and trigger slides back when the arms are to be drawn. This conforms more closely to the images on Trajan’s Column.

One of the few aspects of Nick’s design that I disagree with is that rather than having any of the stock/case forward of the arch, I think only a grooved rail, similar to the traditional slider, should extend beyond the front of the frame. In Aitor Iriarte’s reconstruction of the cheiroballistra or hand ballista, the stock has to extend forwards as well to support the slider when it is run out to capture the bowstring. Since the larger Carroballista has a winch and sliding block and is not a belly-cocker only the fixed rail (quadratus stylus) must extend beyond.”
P. Clodius Secundus (Randi Richert), Legio III Cyrenaica

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It is the intent of today’s posting to help sort out this area of disagreement once and for all.  To that end, here is an image of that forward extending rail  from Trajan’s Column that we here at the LCF put so much stock in. (Arf!)

As I understand it,  Randi’s objection is not so much that something extended beyond the frame,   but that the thing that extended was only the iron rail itself,  with no supporting structure of wooden stock accompanying it.   That may well be,  and I would go so far as to say that what we see in the above depiction does indeed look very much like that.   If the extended part of iron rail was heavy duty enough, I do not doubt it could work like that;  although it seems a heavy and expensive solution to gain the required rigidity.

And it is this rigidity that is at issue here.   Without a substantial enough depth of cross section in whatever extends beyond the frame,  I believe it would be asking for trouble in either how well the catch completes its lock on the bowstring, or by allowing vibrations in an unsupported rail  to affect the precision of the whole system.  Just as the final portion of rifling in a gun barrel has the most effect in the final stability imparted to the bullet,  the last few inches of launch ramp on a ballista might be expected to influence the natural flight of the bolt.  The last thing you’d want would be a flippy rail having its say at the crucial moment of departure.

To my way of thinking, the easiest way to create a sturdy and stable  fore-end that will support a static iron rail,  is to extend the wooden stock the required amount.   Even though Firefly sports a much deeper wooden  fore-end than the carvings on Trajan’s column might suggest,  the principle must surely be the same.  Rigidity! Rigidity! Rigidity!

And now, I have laid my throat bare,  we await Randi’s counter riposte ….

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….. And with timely delivery,  Randi says:

“Thanks for reposting and considering my RAT post. Healthy debate, exchange of ideas, and rigorous testing are the only ways we’ll ever solve the riddles of the catapult. That said, we are perhaps a bit further apart on this issue than my post may have led you to believe. My theory, based primarily on my minimalist approach is that the projecting rail is made of wood. If there is any metal, it is more protection of the bearing surfaces.

Since most of the rigidity is needed aft of the ladder where it is supported by the case, I suspect that much less is needed forward, as seen on Trajan’s. As you have previously demonstrated, there is not a great deal of downwards pressure exerted by the bowstring and an experienced operator can tune the weapon to reduce lateral forces. With the winch pulling from directly behind down the center line I think the accuracy will be fine.”

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To which we counter-counter riposte:

It sounds like a matter of definition to me.  If the projecting rail is made of wood, and that wood is integral to the stock aft of the frame,  (and why wouldn’t it be if we are talking about a static rail?)  then why is a projecting wooden rail with metal surfaces any different than a projecting wooden stock with an integral metal rail installed on it for the same reasons?  The rail doesn’t move.  It sticks out beyond the frame.  It is made from a combination of wood and metal.  I don’t see where you are suggesting anything different in principle than what we currently have working so well on Firefly.

Brother, you should see how sweetly that bronze shoe on the catch assembly rides up and down our steel rail.    It would all be pretty simple stuff for ancient metalworkers to fabricate.  Just forgings and castings and copious amounts of hand filing or grinding.  Of course, whatever they came up with wouldn’t look exactly like our efforts here.  But wood and metal out beyond the frame to form some kind of static rail — now if that is what you are saying, it seems like we are in agreement.

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And then with a flourish, Randi counter-counter-counter ripostes…….

….. Or not.

Randi?    Where did you go Randi?

Are you saying poor old Firefly’s proboscis makes her look fat or something?

Just don’t know how I’m going to break this to her.  You know how sensitive she is about nose jokes….

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But, with undiminished enthusiasm,  Randi returns with a diplomatically angled uppercut:

“I’m still here. I’ve just been busy with that four-letter word, work. First, please remind Firefly that a stong Aquiline nose is the hallmark of Roman beauty.
That being said, I prefer to think of the projecting rail, aka Quadratus Stylus, as wooden throwback to it’s predecesssor the Canalis Fundus. The case remains clamped beside and below it, but in this instance it stops halfway along it’s length when it terminates at the ladder. To better support the sliding block and prevent whippy-ness it is logical to imagine that the grooved rail would need to be beefed up a bit from its 1/4D width as decribed by Vitruvius, and that is why it appears more substatial in the images on Trajan’s.
While it could very well have had the groove or even the entire upper surface clad in metal, and I agree that an entirely metal rail was not beyond the capabilities of Roman craftsmen. I prefer the approach that if it hasn’t been found as an iron artifact, specifically described as metal in a text, or doesn’t absoultely have to be made of metal for structural reasons, I will go with wood. As you may recall, one of my greatest criticisms of other theorists is their penchant for solving problems they can’t understand by adding chunks of bronze. As a machinist you tend to answer questions with iron, as the son of a carpenter I tend to answer them in wood.”

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And then, with a few loose teeth and a splitting headache from all this excitement,  Nick says:

Okay,  I’ll cop to it.   Perhaps Firefly is a tad more ferrous than is ideal.  But there is a logic to it.  And it’s the same logic by which we have chosen to play this game from the start.

Our attempt has always been to maximize the potential evident in the Orsova artifacts, in the belief that the artifacts themselves were so brilliantly configured that the most realistic thing we could do would be to continue the design trajectory they had so conveniently provided a signpost for.    And that, of course,  as we mentioned in the very first posting of this ongoing epic, would be the blacksmith’s approach rather than the carpenter’s.    At one point I’d actually considered a knock-apart iron stand assembled with wedges as a further expression of this predilection.  Fortunately, Randi set me on a better course, and I couldn’t be happier with the result.

So yes, if Firefly gets dropped in the lake, she’s definitely going to the bottom in record time.  Other than that, and if we discount any pretension to proclaiming with certainty what the original machine looked like,  I believe that her record as a functioning test bed for the geometry of the original artifacts at least mitigates any deficits she might possess by the possible under-utilization of timber in her construction.

This really is all just a game.   It’s reality exists largely in those screaming parabolas we have started describing in the sky.  To which end,  our labors continue.

Thank you for this exchange Randi.  It has been refreshing.  And, of course, there is that nonsense about the “even” tangs on the Kamarion we have to clear up.  But that can wait.   Right now, there are more more kinetics to be indulged ….