Sub Articulo 140.4

> \begin{center}
> \begin{figure}
> \includegraphicx[....]{abc.eps}
> \caption{..}
> \label{..}
> \end{figure}
> \begin{figure}
> \includegraphicx[....]{def.eps}
> \caption{..}
> \label{..}
> \end{figure}
> \end{center}
Anyway, this is probably not what you want. It puts two floating
objects inside a center env. The floatings float away, and you're left 
with nothing inside "center". Use
\begin{figure}
  \begin{center}
    ... whatever ...
    \caption{One}\label{one}
    ... whatever ...
    \caption{Two}\label{two}
  \end{center}
\end{figure}
to keep your two graphics together in one floating figure, each
graphics having it's own caption.