\begin{table}%t1
  \caption {\label{tab1}Timing properties of the BiCG-P iterative scheme.}
  %\centering
\par
\begin{tabular}{c c c c c c c}
\hline\hline
  $N_{\tau}$ & 5 & 8 & 11 & 14 & 17 & 20 \\
\hline
  $t/t_{\rm ALI}$ & 0.85 & 1.2 & 1.8 & 2.1 & 2.3 & 2.7 \\
\hline
\end{tabular}
\end{table}