2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/10330A complete catalogue of galaxy cluster models can be used to constrain cosmological parameters like $σ_8$, the amplitude of the initial density fluctuation spectrum. We focus here on two strong lensing statistics for clusters of galaxies: the fraction of rich Abell clusters that are critical to lensing, and the abundance of arcs in such clusters, especially the X-ray luminous ones. The specific aim of this paper is to constrain $σ_8$ for the standard Cold Dark Matter scenario within an Einstein-de Sitter universe.6 pages including 3 figures, gzip'ed and uuencoded Postscript, To appear in proceedings "Mapping, Measuring and Modelling the Universe", Valencia 1995, eds. P. Coles and V. MartinezAstrophysicstext