US Gold Coin Counterfeit Detector From 1855

G'day, interesting piece.
I have a similar device for use with British Sovereigns.
I have seen one for Guineas.
I have seen one for two coins: sov & half-sov.
I have never seen one capable of use with six different denominationd.
I'm impressed with this unit.
I think I paid $50 for my scale, in a nice little timber box.
Very collectible, if you ask me.
Peter in Oz

I don't think it is a counterfeit detector as much as its a filed edge detector. People used to file the edges off of gold and silver coins (which makes it has less precious metal and makes it not worth face value) and save the shavings from allot of coins until they had enough to sell to a scrap metal dealer

not sure I understand how that thing would weigh a coin but if you say so

Wow, that is an impressive little piece of 19th century engineering Quite ingenious how all of the holes are perfectly positioned to be counterbalanced for genuine coins.

The distances from the center of the coin to the fulcrum are inversely proportional to the denomination (and therefore weight) as would be expected for a balance. That is, the $20 is half the distance of the $10, while the $5, $3, $2.5, and $1 are distanced in the proportion 1 to 5/3 to 2 to 5, respectively.

It's not obvious to me how to use it. I guess you could balance it with a known good $20 piece and then use it to measure other $20s or $10s.

The photos aren't very good as far as showing the bottom side of it.

[edit: Ah, there's a missing counterweight. This would be a weight you put in the $1 position in order to check $10 and $20 gold pieces. Without that weight, the balance would be set for $5, $3, $2.5 and $1 pieces. The weight of the counterweight would be something around 6 to 7 $1 gold pieces, so it must have been a fairly thick brass cylinder with the diameter of the $1 coin. ]

Biokemist & Tenacious are "on the money".

Brannenweorks: "It's not obvious to me how to use it. I guess you could balance it with a known good $20 piece and then use it to measure other $20s ..."
- Perhaps I ought to clarify - this device doesn't tell you the weight of a coin, as many other scales do, in terms like "7.98 grams". It is a pre-set scale: it only tells you "right or wrong". If you put a genuine $5 coin in the $20 or $10 positions, it will show up as "wrong", but if you put the same $5 coin in the $5 position, it will show as "correct".

The genius and beauty of this device is the precise placement of the six positions, and the construction of the whole beam so that each coin is balanced by the rest of the structure.

Peter in Oz
Temp: 32.2°C
Wind: E at 9.4km/h
Pressure: 1014.9hPa
at 11.24am

Nah, my guess was right on the money. Here's instructions on how to use the scale:

"You need a small counter weight which fit in the $1 slot. This weight is needed to weigh the 10 and 20 $ coin!
This hard to find weight is often lost, so also by this scale ;-/
http://www.scales-and-weights.com/s...allender.htm

Hey Peter, I'll be visiting Oz soon, just bought tickets. I'm giving a paper on Feynman's path integral, spin, and the generation structure of the quarks and leptons at the Foundations and Frontiers of Physics conference in Perth, Australia in late November.