brontograph

from The Century Dictionary.

• noun Same as brontometer.
• noun An apparatus devised by Marvin (1899) for recording any wave of sound, as thunder or the discharge of a cannon.
• noun A map or diagram showing the progress of the front of a thunder-storm by means of isobronts or equivalent lines for successive hours.

from the GNU version of the Collaborative International Dictionary of English.

• noun A tracing or chart showing the phenomena attendant on thunderstorms.
• noun An instrument for making such tracings, as a recording brontometer.