In that secret compartment they would hide information on microfilm. So literaly you could have a 100 page book in that coin on microfilm.

Is that true? I'm surprised that they had microfilm in 1854. But having checked, it was invented in 1853 by John Dancer, a British optician. It just seems odd ...

Thanks for the link, that helped. See you have an offer already, I will see if I can sell mine too. You selling yours for 195 pounds ?

It's not actually my listing - was trying to find out how much they go for. I've contacted the seller to try and find out what the offer was, but no response as ...

These are the best of my collection.The big gold one with the traveller on it is my favourite. The coin with the hidden compartment on it is old,it says,'Napoleon III Empereur 1855' on the one side and ,'Empire Francais Dix Centimes' on the other side.

Turns out I have a Napoleon III Secret ...