  In this work, after reviewing the theory of the elastic properties of
Strontium ruthenate, an extension suitable to explain the sound speed
experiments of Lupien et. al. \protect\cite{lup2} and Clifford et. al.
\protect\cite{clif1} is carried out. It is found that the discontinuity in the
elastic constant C$_{66}$ gives unambiguous experimental evidence that the \sr
superconducting order parameter $\Psi$ has two components and shows a broken
time-reversal symmetry state. A detailed study of the elastic behavior is
performed by means of a phenomenological theory employing the Ginzburg-Landau
formalism.
