OK, here's some more information. After careful cleaning, I found the following on the top rib. "(illegible).....CO. WHITNEYVILLE, CONN. HOMOGENEOUS WROUGHT STEEL E.WHITNEY'S PATENT OCT. 22, 18??" It's hard to read, but if I had to guess, I'd guess the last two numbers of the year might be 66. At least now I have a little bit to go on.