Often antique furniture may appear to be misshapen or damaged.  A round tabletop may look oval.  An armoire’s framed panels may appear to have cracked or split.  Often this is a result of the wood shrinkage.  Wood shrinks when it is placed in an environment of lower moisture content.  On average, wood shrinks twice as much “across the grain” as it does “with or through the grain”.  The width &, to a lesser extent, the thickness will shrink, because they run “across” the grain pattern.  The length will remain the same, because it runs “with” the grain pattern.  Certain kinds of subtle distortion due to wood shrinkage are expected in antique furniture.  If there is no evidence of wood shrinkage in a “period” piece, then there is a good chance that it is not an antique.

Above is an 18th century tip-&-turn table.  If it is a period piece, then the top should measure to be narrower in width (across the grain) than in length (with the grain).