I’ve been pondering this lately after playing a lot of Assassin’s Creed 2 where they appear quite more often than they do in real life (they’re one of the game’s stock “urban climbing aid”, particularly in San Gimignano)
I’m talking about those external iron or cast iron bars running along the wall, as seen in this picture. See that diagonal thing left of the big archway, beneath the first large window and on the same horizontal pane as the smaller windows of the left building ? At the point where light turns to shadow on the wall ?
What are those called, and what’s their purpose ? Is it purely ornamental ? Structural reinforcement ? Artefact from the construction process ?
It’s not. It’s an iron bar secured parallel to the wall by an embedded iron loop or ring in the middle. Compare to the row of six spikes just under the big windows : those stick out perpendicular to the wall. I’ve also seen examples where the iron bar had two iron rings, at roughly 1/4th and 3/4th of the length of the iron rod. Those are usually vertical though.
But even if I’m mistaken assume it *is *running along the wall, because that’s what I’m talking about :). I just couldn’t find a better or clearer picture because since I don’t know what they’re called I didn’t know what to search for in the first place. “medieval iron wall thingy” yields surprisingly few relevant results
I’m with kferr on this one. There will be a long iron rod that runs from the wall you can see to a parallel wall further back and the bit you see is just to pin it in place. It stops the wall bowing out.
So, what you’re saying is that what I thought was the purpose of the thing (the external iron fixture) is actually sort of a peg for a primitive rebar system going perpendicularly through the wall, either through the floor stones or the beams supporting them ? If so, that makes a lot of sense.
Reinforcement. I have seen things like this on all kinds of old walls and buildings. And they don’t normally appear like they were installed during original contruction. They are added after the fact by people or agencies concerned with the structure’s preservation.
I was told many years ago by my physics teacher that these bars were pre-tensioned to pull a wall back into true. The method was to heat up the metal bar by wrapping burning rags round it, the end plates would then be screwed tight and when the bar cools it would contract and exert extra pressure on the wall, so pulling into place and holding it there.
No I was thinking of something like this: http://img826.imageshack.us/img826/6469/sdc13177.jpg (Sorry, best pic from a quick search. I just remembered seeing them in Moritzberg, Germany and went straight to my folder)
If you look on the wall to the right, the top of it has iron joints. The joints seem to have been added much later than actual construction. Seems that their purpose was to preserve an old structure and ensure it doesn’t fall about from age.
I’ve seen stuff like that a lot on old buildings and structures. Wonder how many times I mistook an anchor plate for structural reinforcement.
Yes, look at the wall on the right of the picture. The wall is clearly made of stone. Holding the sections together are approx. 10 inch long, 2 inch wide iron shanks. You can see them in the picture because they are shinier than the stone they are attached to.
Examining these things closely, it appears that they were not part of the original design, but added later to keep things from falling about.
I read in David Macaulay’s Castle that medieval castle battlements were sometimes equipped with slots to insert timber posts, the purpose of which was to hold up the “hoardings” installed when a siege was imminent. Hoardings were covered wooden platforms which projected from the wall and allowed the defenders to drop discouraging objects, through gaps in the hoarding-floors, directly on the heads of the attackers below. (Later, permanent hoardings were built of stone and named “machicolations.”) Based on their placement, those bars in the picture might have been intended for that purpose, originally.
Or, maybe just reinforcement of the wall, as everyone else seems to think.
I was watching a house make-over show on TV recently, and this technique is still used to stabilise bulging walls on even quite modern buildings. The only difference is now you don’t have to have an anchor plate showing on the outside. What they do is drill a hole through the brick or stone wall, insert the rod through the hole and screw it into something solid, like a wooden floor-joist. They then cut off the rod flush to the wall and anchor it in place with a very strong adhesive. The final job is to cover over what’s left of hole with some cement and you have an “invisible mend”.