I am no expert on U.S. or international patent law. However, if you are concerned about originality issues, have two witnesses sign and date a description or "disclosure form".
Keeping in mind that patents really only give you greater force in pursuing (and paying for) a law suit, consider what patent attorney David Pressman wrote in his book, "Patent It Yourself", 1992 on page 3/6: There's a myth that you can document the date conceived of your invention (or even protect your invention) by mailing a description of your invention to yourself by certified (or registered) mail and keeping the sealed envelope. In fact law regards the use of these "Post Office Patents" as tantamount to worthless and no substitute for the signatures of live witness on a description of your invention, or even for the PTO's Document Disclosure Program. The PTO's Board of Appeals and Patent Interferences, which has great power in these matters, has specifically said that it gives a sealed envelope little evidentiary value. Claude Hartman 35.13N 120.58W
