Let X be an irreducible rational
nodal curve of arithmetic genus g ≥ 2, and let ℒ be a non-special, effective invertible
sheaf on X. Let W(ℒ) denote the set of smooth Weierstrass points of ℒ and all its
positive tensor powers on X. In this paper, we study the distribution of W(ℒ) on X.
In particular, we will show that W(ℒ) is not dense on X, generalizing an example of
R. F. Lax.