patent dates

[CAP]

I found part of an oil lamp with a patent date stamped on the adjustment knob. It read, "Patent Dec. 10, 1867". My question is, how many years would they continue to stamp this date onto the product? Can you establish a probable window of time for the manufacture date of this lamp?

Thanks,

Cap

 

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[lab rat]

I suspect that the date of manufacture had nothing to do with the patent, and that the date you show is the date of the actual patent. If you want to research the actual patent, use that date.

As for how long would they continue stamping it into the product... In those days I think they continued until they stopped manufacturing that particular prototype, whether they replaced it or discontinued it.