Tuatochrone or Tautochrone: How To spell?

The word Tuatochrone is misspelled against Tautochrone, a noun meaning "A curved line, such that a heavy body, descending along it by the action of gravity, will always arrive at the lowest point in the same time, wherever in the curve it may begin to fall; as, an inverted cycloid with its base horizontal is a tautochrone."