Henry Wetherel (father & son--same name, except son added 2nd 'l' to surname) were planemakers and blacksmiths who worked part of their lives in Chatham, CT (not Chatham, Mass). There are also Wetherel(l) imprints with other nearby town names (Glastonbury CT, Middletown CT, and Norton MA). The Father's working dates were 1760's thru 1790-ish, son's dates were 1790-1830-ish.
Maybe they named the town after some of your kinfolks!
Thanks to John Fitzpatrick for supplying all the info.
That 1/2" dado works perfectly, and cuts a channel that is as close to 1/2" as I can measure, without mic'ing it. Kinda blows my mind. It has a wooden thumbscrew through the side to hold the depth stop in place.