• (n.) An instrument or apparatus employed in the ancient mysteries to imitate thunder and lightning.
Ce·rau'no·scope noun [ Greek ... thunder and lightning + -scope .] An instrument or apparatus employed in the ancient mysteries to imitate thunder and lightning. T. Moore. 
ceraunoscope An apparatus used by the ancients in their ancient mysteries to imitate thunder and lightning [as defined by Webster's New Unabridged International Dictionary, 2nd Ed. (1952) and The Oxford English Dictionary, based on an 1827 reference].