Kensey John's Grist Mill, also known as Black Rock Mills, is on the site of an earlier mill owned by Thomas Matthews and sold by his widow in 1794 to Richard Johns.

Kensey, Richards son, built the present mill and his name appears on a datestone between the two upper windows on the 2.5 story end, along with the year 1806.

It was operated as a mill until the 1930's. The mill still contains one of the French burr millstones as late as 1980 and exhibits multiple doors on both gable ends and a corner chimney.

Some other owners were: Shadrack Kemp 1873; John Millender 1875; Henry F. Zouck 1876; P. G. Zouck 1892; Alexander McCurdy 1903; Charles Mann 1905; and Thomas F Gray 1908.

Gray installed an electric generator and motors c. 1910. Mc Curdy installed rollers sometime after 1903.

Across Falls Road on the west stands the miller's house. The mill was a Store, Public house, post office, lodge for community of summer houses, now a private single family dwelling.

The miller's house was once called Grays Rocky Lodge in the first decade of the 20th century when Thomas Gray owned the mill. GPS: 76' 43.94W, 39' 32.44N