We introduce some techniques for making a more global analysis of the
existence of geodesics on a Seiberg-Witten Riemann surface with metric
ds(2) = \lambda sw\(2) Because the existence of such geodesics implie
s the existence of BPS states in N = 2 supersymmetric Yang-Mills theor
y, one can use these methods to study the BPS spectrum in various phas
es of the Yang-Mills theory. By way of illustration, we show how, usin
g our new methods, one can easily recover the known results for the N
= 2 supersymmetric SU(2) pure gauge theory, and we show in detail how
it also works for the N = 2, SU(2) theory coupled to a massive adjoint
matter multiplet. (C) 1997 Published by Elsevier Science B.V.