By a manifold we mean a Hausdorff locally Euclidean space. The purpose of this paper is to prove: THEOREM 1. If the continuum hypothesis is true, then there is a perfectly normal, Hausdorff, nonmetrizable manifold. The question of the existence of such a space was raised by R. L. Wilder [6]. There had been renewed interest in this problem because of M. Reed and P. Zenor's proof [4] that (perfectly) normal, locally compact, locally connected, Moore spaces are metrizable. However recently K. Kunen [2] used the continuum hypothesis to describe a perfectly normal, 1st countable, locally compact, hereditarily separable, non-Lindelgf topology on the line, refining the usual topology. His construction is the basic tool for our solution of Wil...