\begin{table}%t2
%\centering
\par
\caption{\label{table:2}Definitions of low and high tensile strengths. (See text for details).}
\small \begin{tabular}{c c c c}
\hline\hline  \noalign{\smallskip}
Tensile strength & $m$ & $k$ & $\sigma_T($3$ {\rm cm})$ \\
&&(cm$^3$)&(dynes/cm$^2$)\\
\hline\noalign{\smallskip}
low & $9.5$ & $8 \times 10^{37}$ & $\approx$$3.5 \times 10^7$ \\ 
high & $9.5$ & $3 \times 10^{28}$ & $\approx$$3.5 \times 10^8$ \\
\hline
\end{tabular}
\end{table}