The clock trade calls this design an octagon drop (or drop octagon). Most people know it as a schoolhouse clock. I believe it. You don't get a sense of scale with these photos, but this is a big one: 26 inches tall by 16 inches wide. That big face is easy to read mounted on a wall across the room.
This one is an 8-day, time-only movement with a left-hand wind. It's an icon in my family: it was on the dining room wall of both houses I lived in. Now it's on mine. Didn't know what it was until it recently stopped running. To open it you take the hands off, then the screws on the bezel, and the face and bezel and glass all lift off. Inside the movement is fairly small considering the size of the cabinet. I was shocked to find that for once the movement was stamped with the maker: Sessions of Forestville, CT.
Sessions made mechanical clocks from about 1903 to 1939, after which they went electric. So this clock was made sometime in that period. Merritt's Antiques has one that's identical except for a slightly different numeral style on the face. They estimate it from the 1930s. I'm tempted to buy it but I can't imagine what I'd do with two of these.
Besides its size, what makes it almost unique in my house is that it's time-only. Just about every other American clock going back deep into the 19th century that I've seen are strikers. Maybe it's so the clock is quiet and the strike won't interrupt people. Either way, the only other mechanical clock I have that's time-only (not counting the 400-days) is a little bedside clock, and even it has an alarm.
When I get around to attempting to fix this thing, I have to see if I can address the issue of the bezel. Right now it's held by four tiny wood screws and they're the next thing to stripped. The glass (yes) is somewhat heavy, and I fully expect that one day when I open it, the whole asseembly is going to come off in my hand and fall to the ground and shatter. But then, I just had a picture fall of the wall and the glass shatter, so maybe I'm just sensitive to it.
Acquired: unknown. Been in the family since time began. If I recall, this may be the one my paternal grandparents found on a junk heap. Or may have acquired it from a 2nd-hand shop.
Current condition: runs fine.