New Pound Coins

[jack]

http://www.bbc.co.uk/news/uk-politics-26632863

Design

I like it. I think it's the first new coin design I've actively liked, although I came to like the £2 and £5 coins a lot later. I like the word "dodecagonal". Yay for being shaped like a thruppeny-bit :)

Backwards compatibility with existing £1 coins

The BBC article says the Royal Mint said the coin will be about the same size as the existing coin and "will be expressly designed to fit existing mechanisms". But I've not seen the original text of that announcement, or any details on how or why, or whether it means "it will work in existing shopping trolleys" or just "it's POSSIBLE to construct shopping trolleys that accept them", or whether vending machine manufacturers and supermarkets agree or not.

If a dodecagon is just close enough to a circle?

The usual way of making a rounded polygonal coin is a Reuleaux triangle, a polygon curved so any diameter has the same width as a circle, so it rolls smoothly through a fixed-height channel, even though the centre isn't at the same height. But that only works for polygons with odd numbers of sides (else you have a point opposite a point, and if you maintain the same width, you just get a circle). So it doesn't work for 12-sided.

Authentication

http://www.royalmint.com/business/circulating-coin/isis

It apparently includes some sort of authentication thing like banknotes, but no details exactly what.

Pseudomonas asks on twitter, "This doesn't let the government track who spends individual coins, right? Right?" But I've not heard an answer yet.

Comments

[simont]

It would seem very weird for "will be expressly designed to fit existing mechanisms" to mean "it's possible to construct shopping trolleys that will accept them" if it also means the shopping trolleys that already exist will not necessarily do so! I can't see any reading of "fit existing mechanisms" that doesn't involve, well, fitting into mechanisms that already exist.

I think I skimmed past a link this morning somewhere or other suggesting that vending machine manufacturers are unsurprisingly unconvinced.

[hilarita]

It's hard to see how something like the new £1 can be sufficiently like the old £1 for both of them to work in mechanisms, and yet not let some mechanisms (e.g. machines where you don't get the money back) be fooled by a forgery. Which is why we need a new £1 anyway.

[jack]

Well, presumably the ideal would be that the new one would be accepted everywhere the old one was, but is unforgeable in machines which are specifically looking for it. But that didn't immediately seem possible.

[jack]

Yeah, that's what it *sounded* like, but I don't want to underestimate the ability of press releases to say whatever they want and justify it *somehow*...

[gerald_duck]

I reckon they should have gone with an eleven-sided coin: homage to the threepenny bit, but Reuleaux.

Also, currently we have pairs of coins: 1p,2p 5p,10p 20p,50p £1,£2. It seems a shame to break that scheme. I wonder when they'll do something to the £2 to match.

On the other hand, it's bugged me that the magnitudes go 1p,2p,5p 10p,20p,50p £1,£2,£5 etc. where the coins go in pairs. They really ought to have had small, large, seven-sided in each of copper, silver and gold to keep things nice and regular.

Meanwhile, it's high time they reinstated the traditional backs for the smaller coinage. Five years on, I'm still hating the new-fangled backs. )-8

[gerald_duck]

Meanwhile, people in the Computer Laboratory's Security Group have noted that it would be trivial to keep track of which serial number banknote was dispensed to which customer from an ATM.

They noted that before Snowden. Nowadays I'm inclined to assume that because they can do it, they do do it.