The tautochrone problem, the attempt to identify this curve, was solved by Christiaan Huygens in 1659. He proved geometrically in his Horologium Oscillatorium, originally published in 1673, that the curve is a cycloid.
The tautochrone problem, the attempt to identify this curve was solved by Christiaan Huygens in 1659 He proved geometrically in his Horologium Oscillatorium, originally published in 1673, that the curve is a cycloid.