Hi plutodog18, and welcome.
You didn't say where you are â€” it helps if you include your country in your profile.
If the triangle is point up, then it most probably is the mark of the Cambridge Glass Co., Cambridge, Ohio. My source dates the mark to 1901â€“58, a rather long span.
Oops, sorry Glen, I hadn't seen your reply. I've left mine as it has a little more detail from Notley / Miller's.