Nice. I never even noticed that… although now that I’ve taken a closer look that black thing behind the bill with the board certainly could be a dye pack!

Lots of interesting engineering stuffed in there… I’m going to have to do a bit of research. There’s got to be an article somewhere. I’d imagine that a great deal of care went into something of this kind; you’d want it to go off on a delay, never in the bank, potentially if the money was removed from the envelope… that’s probably where the string comes into play.

Fascinating!