Dale: Check the stamping again. Does it say 1899 or 1898? Most of the plugs use the 1898 patent. Which I have narrowed down to one of these: 612,614 612,615 612,701 612,779 612,783 612,801 612,802 There were no patents issued on October 18, 1899. Could you send me a picture of the plug? Thanks, Rich