The W&W #8 was produced from approximately 1878 to 1889. Unfortunately we have no SN records of them as we do on Singer machines. I have copies of a couple of Bill of sales that help narrow it a bit. Problem here of course is we don't know how long a period existed from them leaving the factory until they were actually sold at retail. First one is SN 327,542 & is simply dated 1883
2nd one is SN 509,994 & is dated Sept 15 1885.
Your 5-digit SN is obviously much earlier than either of these. Also most #8 machines will be found with a patent date of Aug 27, 1878 on them. They may well have already had a good number of plates made up prior to the issuance of the 1878 patents (two in fact on the same day) so we can't really say it was made prior to that patent date. My best guess though is it was made no later than 1879.
