What's the tip-off that this is a 19th century copy of an earlier chair?
The turnings are to thin on the 3 central posts, in the 17th century they would have been much thicker, massive in fact, so thick a man could not touch his fingers on the central posts, 2 inches in diameter or more. These chairs did have function in the 1600s as floors were not even/level to say the least, often just packed earth so 3 legs would have been useful on uneven floors/dirt.