NYS Routes of the Boston and Albany

I've read about the B&A having a connection in New York State other than the one that is presently used. I have also read about the branch out of Hudson, which used to connect with and was affiliated with t he B&A. Somehow the NY components of the B&a aren't really known to me. Someone posted long ago about there being traces of the original NY connection to the Western. Would someone please explain what was there?

The line from Chatham to Hudson was always just a branch. It's still pretty visible in satellite images.