I'm looking for information on a maker's mark we found on a bottle base from a site in south-central Wyoming. The mark appears to be "I co" with a straight line connecting the top of the "c" and the "o" (the last two letters are lower case relative to the height of the "I:"). The "I" (if thats what it is) is quite crude -- not much more than a straight up-and-down bar with slight flairing at both ends. The base is aqua-blue in color. There are air bubbles visible in the glass. The diameter of the base is ca. 3". Manufacture is probably some type of early machine mold. The rest of the assemblage appears to be mid-1880s to 1920s. I can send a low res. scan of the base if anyone is interested. Thanks, Tom Larson LTA, Inc.