  Let H and K be subgroups of a free group of ranks h and k \geq h. We prove
the following strong form of Burns' inequality: rank(H \cap K) - 1 \leq
2(h-1)(k-1) - (h-1)(rank(H \vee K) -1). A corollary of this, also obtained by
L. Louder and D. B. McReynolds, has been used by M. Culler and P. Shalen to
obtain information regarding the volumes of hyperbolic 3-manifolds. We also
prove the following particular case of the Hanna Neumann Conjecture, which has
also been obtained by Louder. If the join of H and K has rank at least (h + k +
1)/2, then the intersection of H and K has rank no more than (h-1)(k-1) + 1.
