\begin{table}%t5
\caption{\label{tab:summary-metallicity}Metallicity estimates in the 8~o'clock arc.} 
%\centering
 \small
\begin{tabular}{l c l c}   
\hline\hline \noalign{\smallskip}           
Environment & Method & Elements & $Z/Z_{\odot}$ \\
\hline
\ion{H}{ii} regions\tablefootmark{a} & N2                     & O         & 0.83 \\
\ion{H}{ii} regions\tablefootmark{a} & O3N2                   & O         & 0.39 \\
OB stars\tablefootmark{b}	        & ``1425'' index         & C, Si, Fe & 0.85 \\
OB stars\tablefootmark{b} 	        & ``1978'' index         & Fe	     & 0.79 \\
ISM gas\tablefootmark{c}             & Apparent optical depth & Si        & 0.65\\
\hline                       
\end{tabular}
\tablefoot {\tablefoottext{a}{As derived by \citet{finkelstein09};}
\tablefoottext{b}{this work (Sect.~\ref{sect:stellarlines});}
\tablefoottext{c}{this work (Sect.~\ref{sect:columndensities}).}} 
\end{table}