I have this teapot - actually I have two of them. My family settled in Philadelphia in the 1800's and were wealthy. I think this is Hartford Sterling but the H.S. in the shield is different and there is an X with a crown above to the left and a left facing standing lion head at the right of the H.S. in the shield Sterling on Copper is in the traigle and there are engravings that look to be part of a household inventory.[[/img]
I have seen that mark many times, but none of my books identify it. Agree that it's probably a Hartford Sterling Company mark, but have not been able to confirm that.