I'm not a big collector, but I have a smattering of various US fractional notes. I always wondered about the big black "O" that is stamped across the 10 cent. I know this is not on all the 10 series (I believe mine is second series), and I have also seen it on a 5 cent note. I can provide a scan, if necessary, but I think if you are a fractional collector you will know what I'm talking about. Any idea what it is for or why they did this? Thanks.
Dave

That is called 'bronzing' which was done by using powdered bronze in an ink base. This was an anti-counterfeiting device used as an attempt to prevent photographic reproduction.

Thanks for the info. I have 2 of them, but the bronze has turned black. I've seen the bronze color on other bills, but it always seems better coordinated into the design. Any idea why they splatted a big "0" right across the front of this one? Is there any significance to that (ie. why not a "10" like on the third issue or on the back)?
Appreciate the use of your brain.....