X-ray Properties as Probes of Cosmology.

Section 1.3.1 showed how the mass function of clusters is related to the underlying cosmology of the universe and section 3.1 illustrated how $L_{{\rm X}}$ and more directly $T_{{\rm X}}$ may be related to $M_{{\rm total}}$. This section links these two giving examples of observational measurements of the evolution of clusters of galaxies.