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    horn and sinew cross-section puzzle

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    stuckinthemud1
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    horn and sinew cross-section puzzle

    Post by stuckinthemud1 on Mon Aug 17, 2015 8:09 am

    Hi All,

    This composite bow cross-section has always puzzled me.  
    The cross-section shows black horn strips on each side of a light brown block of something else.  The cap of sinew and the wrap of birch bark are straightforward to identify but surely the light brown central block is some other material not identified by the museum (image from Metropolitan Museum of Art, identified as c1450 to 1500 in date, possibly south German or Swiss) so are they a timber such as maple, or stag-horn, perhaps used as a scaffold to support the bow while the glue sets, or something else? Any thoughts??

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    Re: horn and sinew cross-section puzzle

    Post by c sitas on Mon Aug 17, 2015 9:19 am

    Mr.  Stuck, This is my grab in the dark. I think it is horn.

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    Re: horn and sinew cross-section puzzle

    Post by rolynd on Mon Aug 17, 2015 9:28 am

    The best source is  Holger Richters Book "Die Hornbogenarmbrust"  Most of the prods he examined were made from laminated packets of horn strips with a large sinew backing.  AFAIK  there was only one prod which had a thin oak strip as center but it was horizontally arranged. Some  had small short oak strips embedded in the tips of the  prod to strengthen it there.  None of the Horn crossbows he examined had such a large wooden core. Stag horn at this diameter would be too stiff imho to serve  as a center esp if this large. 
    Maybe its just  blond horn  from the horn tip where its more massive.  which would also  explain the size.  Horn is usually a thin walled hollow over a bone core but at the tips where the bone does not reach the  walls come together and form a massive tip. This could also explain the  unusual "grain" you see.   I cut a waterbuffalo horn up once (for other purpose) and   this reminds me of what I saw near the  tip area.  Could also be  they heated and pressed a piece of  horn tip and all that remains from the interior hollow is the thin vertical line in the middle of the light brown larger piece.

    Heating and pressing  horn to obtain large flat pieces was definitely done  in the period but I have no idea if these pieces were used for crossbow building.

    The period technologies  used  are described in :
    Bone, antler, ivory & horn: The technology of skeletal materials since the Roman period Hardcover – 1985 by Arthur MacGregor.
    by Arthur MacGregor  (Author)
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    Re: horn and sinew cross-section puzzle

    Post by OrienM on Mon Aug 17, 2015 12:54 pm

    Definitely doesn't look like wood, or antler. I'd say horn, too...my guess is that they made the belly core out of half a horn pressed flat, planed it square, and then built up the rest of the belly by adding strips to the sides.

    It would be nice to know how long this pressed piece runs along inside the prod. If using a nice, long horn, it seems like making it in two pieces butted in the center would be fairly logical.

    Thanks for posting. Makes me want a toothing plane... Cool

    So what species of horn was mostly used in these? Something of local origin, like goat or domestic cow?

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    Re: horn and sinew cross-section puzzle

    Post by c sitas on Mon Aug 17, 2015 5:04 pm

    Just my thought here, goats that I have seen had some very long horns.
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    Re: horn and sinew cross-section puzzle

    Post by twedzel on Mon Aug 17, 2015 8:28 pm

    It doesn't make any sense for it to be wood. I agree with the general consensus that it is probably horn. Wood in a conventional composite (or fiberglass) bow is basically a light weight spacer used in the core where the dead weight of horn and sinew would hamper performance.

    The standard horn for Asiatic composites is Water Buffalo. Native Americans mostly used sheep horn but there were also reports of using buffalo horn and rib, cariboo antler, or elk antler. I don't know what medieval period horn crossbow prods were made from but I figure some kind of long horned cattle would be a good bet.
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    Re: horn and sinew cross-section puzzle

    Post by Armbrustier on Tue Aug 18, 2015 9:33 am

    Hi all!

    It's very nice to see that this bow part iis still with us. It's from the Zeuhaus in Berlin and I was sadly rather sure that it had vanished during the war. 
    It's a bit wrongly dated, it's probably about 100 years older. My guess eould be around 1400, at the latest maybe from around 1420.

    The center pieces is said to be of baleen, whale bards, but I don't think anyone has checked if that's true or not. It could be baleen as this is nearly the same material as horn, but my own guess would be Ibex horn, that was/is one of the best materials for a hornbow, and it can give quite thick pieces like this.
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    Re: horn and sinew cross-section puzzle

    Post by kenh on Tue Aug 18, 2015 6:49 pm

    Not wood.  It does not have wood grain cross-section.  Not horn, either, because it does have 'grain'.  I would say bone -- an oval bone with one of the narrow ends of the oval cut off and then flattened.

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    Re: horn and sinew cross-section puzzle

    Post by rolynd on Tue Aug 18, 2015 10:33 pm

    If you look at this horm mallet made from cowhorn tip you see there IS sometimes a bit of circular grain. if this were pressed flat and  sanded a bit the circle would deform and if thereis also a bit of cavity left in the center it would make a structure fairly closely resembling what is seen in the above. flattening horn is also far easier than  with bone. Bone has to be softened by chemical treatment to leach some of the  calcium content but the softening would be permanent making it weak.

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    Re: horn and sinew cross-section puzzle

    Post by HeroSK on Wed Aug 19, 2015 3:12 am

    In the book of Alm, it is mentioned that some crossbow prods are constructed with whale bone plates in the middle. This could be the case.
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    Re: horn and sinew cross-section puzzle

    Post by OrienM on Wed Aug 19, 2015 8:01 am

    Are we talking 'whalebone' as in skeletal bone, or baleen? I've handled some baleen plates, and they do seem like good bow material...I've never seen one that wasn't black-colored, though. Are there types of baleen that are blonde?

    I agree with Rolynd...horn absolutely has grain; a rather wood-like structure really, with concentric rings made of linear fibers. The pieces of cow and water buffalo horn I've played with (which were old, and somewhat dried out), you could peel off long splinters from the outer rings by hand. Short pieces of horn can actually be split, just like a block of wood.

    Ibex horn seems like it would be good stuff...

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    Re: horn and sinew cross-section puzzle

    Post by rolynd on Wed Aug 19, 2015 9:12 am

    I think baleen would make more sense than whale bone if it were a Whale-originated material.
    I have never handled baleen  but I was always thinking of it as being relatively thin strips/plates not of the thickness shown here?
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    Re: horn and sinew cross-section puzzle

    Post by kenh on Wed Aug 19, 2015 8:11 pm

    I've never seen anything but black baleen, although it would probably make a pretty good "springy" bow material.

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    Re: horn and sinew cross-section puzzle

    Post by stuckinthemud1 on Thu Aug 20, 2015 7:34 am

    Thanks for your thoughts; my difficulty with it being timber was that the exposed timber would be unsupported by horn and very likely to fail under high stress, therefore horn makes perfect sense.  I did not realise that horn could be pressed and squared, or that it would mimic a form of grain if it went through such a process.  Would baleen, being a different material from horn have a differing level of elasticity and so add stress to a finished bow, increasing the likeliness of failure or reduce its effectiveness?
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    Re: horn and sinew cross-section puzzle

    Post by twedzel on Thu Aug 20, 2015 8:50 am

    From what I have read, baleen can be used in both tension and compression much like fiberglass. But I do not know how effective it is at either. Not many people have the opportunity to play with baleen these days so its true effectiveness may have to go untested.

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    Re: horn and sinew cross-section puzzle

    Post by stuckinthemud1 on Thu Aug 20, 2015 8:55 am

    Agreed, but I wondered whether, if it is stronger or weaker than the surrounding horn, then that difference would add to the bow' internal stresses and result in an inferior action?
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    Re: horn and sinew cross-section puzzle

    Post by OrienM on Thu Aug 20, 2015 2:57 pm

    If it is horn, I doubt if its compression strength is much different from the side-plate sections...horn is very strong stuff.  They oriented the central seam in the strongest possible way, as well.

    In my experience a composite bow tends to act as a unit...the parts are all tightly glued (ideally), carefully tapered and shaped, and mutually reinforcing. A subtle difference in horn quality wouldn't matter very much in this case, especially because the difference would be pretty equally distributed inside the prod.

    However...if there were a serious flaw at a single point along the length of the core, a crack or thin spot, say, then the whole belly would likely fail at that point, and the bow would collapse. An excellent reason for extreme care in materials selection and workmanship, especially in something as time-intensive as a composite prod.

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    Re: horn and sinew cross-section puzzle

    Post by stuckinthemud1 on Thu Aug 20, 2015 3:40 pm

    Which is why I would question the use of baleen - all horn then good and strong, mixed materials could increase the likelihood of a failure??
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    Re: horn and sinew cross-section puzzle

    Post by OrienM on Thu Aug 20, 2015 4:08 pm

    Hard to know without comparing the materials directly, and without having actually worked baleen...unless it was quite a lot weaker, I wouldn't imagine it would causes a failure, as the sideplates and sinew back would still be reinforcing it. Again, the whole bow is working as a unit, and sinew will keep even a less-than-ideal bow together surprisingly well.

    Baleen actually seemed like a fairly horn-like material, from what I recall, although (of course) much thinner and flatter. It has been used successfully in composite bow bellies in modern times. (One is shown in the 'Traditional Bowyers Bible' vol. 1, if I remember correctly...excellent books on technical bowyery, BTW, if you've not read them already.)

    I'd agree that using dissimilar materials probably isn't ideal, but these makers knew to key the surfaces, to taper the pieces so they'd overlap, and to carefully place the joints to avoid weak areas. If they did include baleen, I'm sure they dealt appropriately with it.

    DNA testing of some of these bellies would be very informative...it's so hard to tell much about materials just based on photos.

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