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<p>[QUOTE="Severus Alexander, post: 7955584, member: 84744"]In <a href="https://www.cointalk.com/threads/unstruck-coins.387793/" class="internalLink ProxyLink" data-proxy-href="https://www.cointalk.com/threads/unstruck-coins.387793/">this neat thread</a> on coins with a blank side (by [USER=99554]@Ocatarinetabellatchitchix[/USER]), I posted the following coin. Judging by the obverse, it is a Trier mint product, either RIC 520 or 539, with a missing GLORIA EXERCITVS reverse:</p><p><br /></p><p>[ATTACH=full]1379120[/ATTACH] </p><p><br /></p><p>I asked for opinions on what the odd nub was on the reverse. Normally these blank-sided coins result from two stacked blank flans being struck by accident, resulting in one coin with an obverse plus a blank side, and another with a reverse and a blank side. I've never seen another example with a nub, they're usually smooth with a crescent where the edge of the intervening blank flan was. (There is a similar crescent on my coin, but as you'll see below, I doubt this is an impression made by a blank.)</p><p><br /></p><p>I got a couple of interesting answers:</p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p>I like this theory! I had wondered whether something of the sort might explain it, but hadn't looked into it at all. On the strength of [USER=77226]@Orange Julius[/USER]'s and [USER=56859]@TIF[/USER]'s thinking, today I did. <img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie1" alt=":)" unselectable="on" unselectable="on" /> And ended up putting enough work into it that I felt it should be moved to its own thread.</p><p><br /></p><p>First, a couple of points to note in favour of the theory:</p><p><br /></p><p>1) If there were a simple linear nub and socket system for aligning the dies, as suggested by my coin, then there would be two possible ways to orient the obverse and reverse dies with respect to each other, 180° apart. And this is exactly what we find: these Trier GLORIA EXERCITVS issues always have a 12h or 6h die axis +/- 1. (This seems to apply to the GLORIA EXERCITVS issues more generally.) Also, given the enormous volume of production, we would expect some automatic way of keeping the die axis within such a narrow range.</p><p><br /></p><p>2) According to <a href="http://www2.lawrence.edu/dept/art/BUERGER/ESSAYS/PRODUCTION7.HTML" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www2.lawrence.edu/dept/art/BUERGER/ESSAYS/PRODUCTION7.HTML" rel="nofollow">"The production of ancient coins" by Wickens</a> which purports to summarize our knowledge of ancient coin production, "Some [Roman] dies may have had pegs or notches to help guide the minters in orienting the punch." I'm not sure where he got this information, but it seems the idea has already been proposed, presumably with some support. (That evidence might just be the consistent die alignment I note in (1).)</p><p><br /></p><p>In a few places (for example <a href="https://publications.artic.edu/roman/reader/romanart/section/512#/" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://publications.artic.edu/roman/reader/romanart/section/512#/" rel="nofollow">The Art Institute of Chicago</a>), I found the hypothesis that "the image could be engraved directly into the base of a cylindrical or pyramidal piece of metal <i>or, more commonly, into a bronze disk that was fitted into an iron punch or collar</i>." The disk/collar method would allow for an iron striking mechanism to have new dies easily inserted as needed. The alignment socket would be in the iron base, and the nub in the die disk.</p><p><br /></p><p>Now take a look at the following doctored image of my coin. This is as though the metal is partially transparent, and you're looking directly at the reverse, while seeing a ghostly image of the obverse <i>through</i> the coin:</p><p>[ATTACH=full]1379124[/ATTACH] </p><p>Ignore the blue circle for the moment, and notice this: <i>the edge of the obverse die lines up perfectly with the crescent line on the reverse</i>. That's an odd coincidence if the crescent on the reverse were caused by a blank flan. A much more probable explanation is that the crescent on the reverse is just a product of the obverse die strike. (Imagine doing this to a piece of Play-Doh - the disk would get crushed on both sides along the edge of the die.) The blue circle indicates the position of the obverse die.</p><p><br /></p><p>Another interesting point to note is that the obverse is struck off-centre. Now, the production quality of these Constantinian AE coins was amazingly high, and off-centre strikes are highly unusual. Take a look at the results from <a href="https://www.acsearch.info/search.html?term=constantine+gloria+exercitvs&category=1-2&lot=&thesaurus=1&images=1&en=1&de=1&fr=1&it=1&es=1&ot=1&currency=usd&order=4" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://www.acsearch.info/search.html?term=constantine+gloria+exercitvs&category=1-2&lot=&thesaurus=1&images=1&en=1&de=1&fr=1&it=1&es=1&ot=1&currency=usd&order=4" rel="nofollow">this acsearch</a> - almost every coin is perfectly centred, give or take a tiny bit! Given the volume of production, this is pretty amazing. This suggests to me that, just there was some automatic method to align the dies (the nub/socket), there was also an automatic method to centre the coins. The easiest way to do this is to make sure the anvil die has a depression which is a good fit for the flans - though a bit larger to accommodate varying flan shapes. The result would be almost perfectly centred coins, with a little wiggle room - just as we see.</p><p><br /></p><p>Putting this all together, here is a depiction of a die setup that would explain both the consistent production aspects, as well as my odd coin:</p><p>[ATTACH=full]1379123[/ATTACH] </p><p>In the left cross-section, we see everything operating as it should. There's an anvil which has a depression to accept the replaceable die disk. At the bottom of the die disk is the nub which keeps the anvil die aligned, matching with a socket in the anvil. The flan (green) sits in a depression within the die-disk that ensures proper centring.</p><p><br /></p><p>In the right cross section, the replaceable die disk is missing, with the result that 1) the die-alignment socket in the anvil is impressed into the flan, and 2) the flan is not properly centred, it's free to move within the anvil's depression, and so 3) the hammer die creates matching crescents on both obverse and reverse. Producing my coin, in other words!</p><p><br /></p><p>However... it's not all smooth sailing for the theory, I'm afraid. Here is one significant worry:</p><p><br /></p><p>As TIF notes, on my coin we would expect the impression of the alignment socket to be from the <i>hammer </i>die, given that the portrait is normally on the anvil die. That's not how I've drawn it - instead, my setup involves the portrait being on the hammer die. Now it's of course possible (and even likely) that the hammer die had a replaceable die disk as well, but I'm having trouble imagining a setup whereby that produces my coin. In particular, it seems hard to explain the off-centre strike. If the anvil die disk were present, and it was the <i>hammer</i> die disk that was missing (exposing a socket), wouldn't the flan still be centred properly within the anvil die disk depression? It's hard to imagine a centring mechanism that involved the hammer die rather than the anvil die. (Here I'm assuming the two weird aspects of my coin, the nibbed blank side and the off-centre strike, are somehow connected. That assumption might be false! But we'd still need an explanation for both aspects.)</p><p><br /></p><p>One possible conclusion to draw might be that the portrait was indeed on the anvil die for producing these Constantinian coins. Another possible conclusion could be that TIF's improbable hypothesis is actually correct - my coin was produced in the normal way, with two blank flans, one of which just happened to have a weird rectangular divot in it.</p><p><br /></p><p>What do you think?</p><p><b><br /></b></p><p><b>And please post your family of Constantine AEs, especially the imperfectly struck ones!</b>[/QUOTE]</p><p><br /></p>
[QUOTE="Severus Alexander, post: 7955584, member: 84744"]In [URL='https://www.cointalk.com/threads/unstruck-coins.387793/']this neat thread[/URL] on coins with a blank side (by [USER=99554]@Ocatarinetabellatchitchix[/USER]), I posted the following coin. Judging by the obverse, it is a Trier mint product, either RIC 520 or 539, with a missing GLORIA EXERCITVS reverse: [ATTACH=full]1379120[/ATTACH] I asked for opinions on what the odd nub was on the reverse. Normally these blank-sided coins result from two stacked blank flans being struck by accident, resulting in one coin with an obverse plus a blank side, and another with a reverse and a blank side. I've never seen another example with a nub, they're usually smooth with a crescent where the edge of the intervening blank flan was. (There is a similar crescent on my coin, but as you'll see below, I doubt this is an impression made by a blank.) I got a couple of interesting answers: I like this theory! I had wondered whether something of the sort might explain it, but hadn't looked into it at all. On the strength of [USER=77226]@Orange Julius[/USER]'s and [USER=56859]@TIF[/USER]'s thinking, today I did. :) And ended up putting enough work into it that I felt it should be moved to its own thread. First, a couple of points to note in favour of the theory: 1) If there were a simple linear nub and socket system for aligning the dies, as suggested by my coin, then there would be two possible ways to orient the obverse and reverse dies with respect to each other, 180° apart. And this is exactly what we find: these Trier GLORIA EXERCITVS issues always have a 12h or 6h die axis +/- 1. (This seems to apply to the GLORIA EXERCITVS issues more generally.) Also, given the enormous volume of production, we would expect some automatic way of keeping the die axis within such a narrow range. 2) According to [URL='http://www2.lawrence.edu/dept/art/BUERGER/ESSAYS/PRODUCTION7.HTML']"The production of ancient coins" by Wickens[/URL] which purports to summarize our knowledge of ancient coin production, "Some [Roman] dies may have had pegs or notches to help guide the minters in orienting the punch." I'm not sure where he got this information, but it seems the idea has already been proposed, presumably with some support. (That evidence might just be the consistent die alignment I note in (1).) In a few places (for example [URL='https://publications.artic.edu/roman/reader/romanart/section/512#/']The Art Institute of Chicago[/URL]), I found the hypothesis that "the image could be engraved directly into the base of a cylindrical or pyramidal piece of metal [I]or, more commonly, into a bronze disk that was fitted into an iron punch or collar[/I]." The disk/collar method would allow for an iron striking mechanism to have new dies easily inserted as needed. The alignment socket would be in the iron base, and the nub in the die disk. Now take a look at the following doctored image of my coin. This is as though the metal is partially transparent, and you're looking directly at the reverse, while seeing a ghostly image of the obverse [I]through[/I] the coin: [ATTACH=full]1379124[/ATTACH] Ignore the blue circle for the moment, and notice this: [I]the edge of the obverse die lines up perfectly with the crescent line on the reverse[/I]. That's an odd coincidence if the crescent on the reverse were caused by a blank flan. A much more probable explanation is that the crescent on the reverse is just a product of the obverse die strike. (Imagine doing this to a piece of Play-Doh - the disk would get crushed on both sides along the edge of the die.) The blue circle indicates the position of the obverse die. Another interesting point to note is that the obverse is struck off-centre. Now, the production quality of these Constantinian AE coins was amazingly high, and off-centre strikes are highly unusual. Take a look at the results from [URL='https://www.acsearch.info/search.html?term=constantine+gloria+exercitvs&category=1-2&lot=&thesaurus=1&images=1&en=1&de=1&fr=1&it=1&es=1&ot=1¤cy=usd&order=4']this acsearch[/URL] - almost every coin is perfectly centred, give or take a tiny bit! Given the volume of production, this is pretty amazing. This suggests to me that, just there was some automatic method to align the dies (the nub/socket), there was also an automatic method to centre the coins. The easiest way to do this is to make sure the anvil die has a depression which is a good fit for the flans - though a bit larger to accommodate varying flan shapes. The result would be almost perfectly centred coins, with a little wiggle room - just as we see. Putting this all together, here is a depiction of a die setup that would explain both the consistent production aspects, as well as my odd coin: [ATTACH=full]1379123[/ATTACH] In the left cross-section, we see everything operating as it should. There's an anvil which has a depression to accept the replaceable die disk. At the bottom of the die disk is the nub which keeps the anvil die aligned, matching with a socket in the anvil. The flan (green) sits in a depression within the die-disk that ensures proper centring. In the right cross section, the replaceable die disk is missing, with the result that 1) the die-alignment socket in the anvil is impressed into the flan, and 2) the flan is not properly centred, it's free to move within the anvil's depression, and so 3) the hammer die creates matching crescents on both obverse and reverse. Producing my coin, in other words! However... it's not all smooth sailing for the theory, I'm afraid. Here is one significant worry: As TIF notes, on my coin we would expect the impression of the alignment socket to be from the [I]hammer [/I]die, given that the portrait is normally on the anvil die. That's not how I've drawn it - instead, my setup involves the portrait being on the hammer die. Now it's of course possible (and even likely) that the hammer die had a replaceable die disk as well, but I'm having trouble imagining a setup whereby that produces my coin. In particular, it seems hard to explain the off-centre strike. If the anvil die disk were present, and it was the [I]hammer[/I] die disk that was missing (exposing a socket), wouldn't the flan still be centred properly within the anvil die disk depression? It's hard to imagine a centring mechanism that involved the hammer die rather than the anvil die. (Here I'm assuming the two weird aspects of my coin, the nibbed blank side and the off-centre strike, are somehow connected. That assumption might be false! But we'd still need an explanation for both aspects.) One possible conclusion to draw might be that the portrait was indeed on the anvil die for producing these Constantinian coins. Another possible conclusion could be that TIF's improbable hypothesis is actually correct - my coin was produced in the normal way, with two blank flans, one of which just happened to have a weird rectangular divot in it. What do you think? [B] And please post your family of Constantine AEs, especially the imperfectly struck ones![/B][/QUOTE]
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