Im not just asking about U.S coins im asking about anywhere, and they must be real coins that circulated not bullion or commemorative issues.
Tough question. I wanna say the silver dollars struck 1794 to 1978. Flowing Hair, Draped Bust, Capped Bust, Trade, Morgan, Peace, and Ike dollars. For smallest, probably the $1 Gold coin or Half dimes.
I Believe The World's Smallest Coin Is The 14th Century Gold Coin Vijanayagar Empire 3/4 Grain Bele DE
For UK coins Largest Copper two-pence of 1797 ... 2oz of pure copper, 41mm diameter. Smallest Maundy (silver) penny same spec since 1822 ... 0.5g, 11mm in diameter - before the early C19th, these would often circulate, being the successor to the hammered pennies Quarter farthing (¼d, 3840 to £1!!) 1839 & 1853 ... 1.2g, 13.5mm diameter Third farthing (1/3d) 1902 & 1913 ... 1.0g, 15mm (lighter than the ¼d, but wider)
For submission of the smallest circulating coin , I submit the Indian gold fanam. from the 14th to 18th century.
I think you are right about the small coin. There was a previous CT thread & someone mentioned a medieval coin from India. Regarding the timed traffic lights, there are many factors to consider but they might also work well at 140 MPH.
Probably not and I don't believe they would work at 70. 17.5 mph would work though. The problem is if they are set for 35 they are set so that if you are setting at one when it turns green, if you travel 35 mph the next one will turn green just before you get there so you don't have to stop. If you take off and do 70 you will get to the next light before it changes. If you travel a little less than 1/2 the set speed the next light will go through nearly two cyles before you get there and when you arrive it will just be turning green again. (This has been overly simplified.)
The fanam mentioned earlier was the first thing that came to mind as the smallest. The Panama Pill is another impressively small coin which is very appropriately nicknamed if you've ever seen one. It's a silver coin with a face value of 2.5 cents; just imagine a half-half dime. Widow's mites are small, but there are plenty of coins just as small. As for the biggest, well, the Yap Stone money didn't exactly circulate in ways that we'd be familiar with. Title to the money changed hands, but the money itself often didn't go anywhere for reasons that would become almost as obvious as your hernia if you tried to pick it up. I don't think it would actually be considered a coin by most definitions. My vote, without doing any particular research on the subject, would be for Swedish Plate Money. Consider a rectangular 18th century copper coin with a face value of 10 dollars, or in this case dalers... which contained its face value worth of copper. These things came in various denominations dropping as low as a half daler, which is still an awfully large chunk of copper. Sweden made plate money because they had no silver but tons of copper, and the plates did circulate. But they proved unpopular (wonder why? ) and were literally used as ballast when Sweden was able to get more silver. Most pieces known today are sea salvaged -- appropriate when you consider that they were used as ballast. Swedish plate money is dated and listed in the appropriate volumes of Krause. There are also some very large oblong Japanese coins, as well as some impressive multiple Talers. Realistically, anything larger than a crown-sized piece is big enough to make people take notice.
I suppose since 1900 the largest circulationg coin might be Mexico's 40mm Cuauhtemoc 5 Peso silver coin struck in 1947 and 1948.
There is a coin dealer in Colorado Springs that has a smaller version of this on display (it's probably about 18" in diameter, by my recollection). He says it's not for sale so I have no idea what it's worth, although I seem to recall a sign that said it could be traded for "one wife or a canoe."
Canada made a 100 Kg gold coin recently. Not really a circulating issue either. But it would be nice to get one in change. Photo from CBC news.
i dont know about the largest but i would say i have pretty close to being one of the smallest. i bought it when i was a kid only because it was gold. its marked madras presidency 1 fanam. my caliper says its 5.7 mm. i need to goto work very soon but might get some pictures of it for the thread when i get back. ah i was beaten to it. i should of payed more attention. ah well. just enough time to do this fast.
The Indian fanams are gigantic compared to this Ionian 1/192 stater. http://www.cngcoins.com/Coin.aspx?CoinID=152972
In theory yes, but the OP asked about circulation coins. As for that Canadian beast, I am not sure to what extent it circulates. Christian