weighes and measures

Used an analog caliper. I do have to wear glasses though...

 

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A picture is worth a thousand words.

 

The coin in question is obviously not MS. If graded would receive vf 30 or 35. I have heard a lor of great comments and theories, but , is it within the realm of possibility that a coin after being in circulation for decades looses some of its diameter? .25 of a mm is relatively miniscule and in figuring a loss on a diameter means that each opposing side would only loose .125 mm if worn evenly.

 

The coin does get hot during striking but not that hot. From images of the coins being struck you can see that it is not hot enough to cause a color change in the metal. It is enough to burn your hand directly after striking but not hot enough to raise a blister. So first degree burns but not second degree. Probably 200 degrees at the most. I don't know where the 38.5 mm diameter came from, the diameter is 38.1 mm. The variation in the Morgans posted earlier from greatest to smallest was .07 mm That is 3/1000ths of an inch. Three of the four are slightly smaller than the spec 38.1 mm, but the smallest one at 38.07 is only 1/1000th of and inch off. The .25 mm that the OP coin is off is 1/100 of an inch, ten times as much. (I would assume the one Morgan at 38.14 must have come from a worn collar, just over 1/1000 of an inch too large.

 

I found a couple of references that mention the 38.5, ( most prominent was Breen and could be the source of the error~ it was for my understanding), but the diameter of the coin doesn't seem to be fixed in the act establishing it http://nesara.org/files/coinage_act_1837.pdf nor in the later one of 1878. The weight in grains and the purity certainly was, but I could find no reference to diameter. If some one else knows, please give the act or legal definition. The majority of references gives it as 1 1/2" which does work out to 38.1mm.

 

Could the real problem be the calipers and scale you are using? Most have a disclamer about their accuracy being off +/- so much. Digital scales must be calibrated every so often and come with a weight to do so. I only use plastic calipers with my coins, and I always seem to be off by 1mm. The cheap metal calipers with the digital box added on are known for being inaccurate. My 2 cents. :foot-mouth:

 

I'm glad you didn't lose it over the course of seven years. I know I would have.

 

The caliper may very well be the issue coupled with operator inexperience. I also have a barber dime that the reed is nearly completely worn off, I want to measure with new calibrated equipment and compare to an MS example. Just curious to see how much the diameter actually decreases. I have seen tons info on what MS examples are supposed to measure but nothing on what the actual reed depth measures.

 

The thickness of my calipers exceeds the width of the reeding valley, so I get the maximum OD either way.

 

I decided to go buy a new caliper. So far I have measured the following...

1881 MS 63 morgan-- 37.98mm
1921 VF 30 Morgan-- 38.12mm
1878 VF 35 trade dollar -- 37.97mm
1974 XF ike dollar-- 38.18
1859 seated dollar 38.04mm ( the one in question).

These measurements may be off by a couple hundredths,
But a couple hundereths are negligible given the miniscule scale.