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.