Our Schlieren imagery did not provide frames showing the deformation
of glass.  We were able to acquire relatively few good video images of
glass cracking.  Figure \ref{fig:schlieren_video_frames} shows our
best captured recording of glass cracking.


\begin{figure}[h!]
\centering
\includegraphics[width=2.25in]{schlieren_heating}\\
\includegraphics[width=2.25in]{schlieren_crack}\\
\includegraphics[width=2.25in]{schlieren_crack2}\\
\includegraphics[width=2.25in]{schlieren_done_cracking}

\caption{Frames from a captured Schlieren video of glass cracking
under heat shock.  The video was taken at 30fps with an NTSC camera; a
frame counter is included in the bottom left corner of the frames.}

\label{fig:schlieren_video_frames}
\end{figure}
