Photos of the Henry Factory on Bushkill Creek, Boulton, Pennsylvania are shown as plates 17 and 18 in The Kentucky Rifle, by Captain John G.W. Dillin, 1924. William Henry, and William Henry, Jr (the Boulton maker) are discussed on page 20.
This shop was later razed by local people afraid of children getting hurt playing there. When I saw the rubble Spring 1963 there was a lime pile, possibly used for annealing steel parts. As it was covered in poison ivy, I was not so enthused about digging. Went there as part of an Ecology Class trip to see the old-growth Hemlock forest, that being the climax growth tree in eastern Pennsylvania.
If perchance you should be so unfortunate as to lack a copy of Dillin, then get thee one. It is the primary book for anyone interested in the American long rifle. Armchair critics will be glad to point out Capt Dillin's errors of 90 years ago.