The origin of the hourglass is unclear. Its predecessor the clepsydra, or water clock, may have been invented in ancient Egypt. According to the American Institute of New York, the clepsammia or sand-glass was invented at Alexandria about 150 BC.[1] According to the Journal of the British Archaeological Association the so-called clepsammia were in use before the time of St. Jerome (335 AD), and the first representation of an hourglass is in a sarcophagus dated c. 350 AD,[2] representing the wedding of Peleus and Thetis, discovered in Rome in the 18th century, and studied by Winckelmann in the 19th century, who remarked the hourglass held by Morpheus in his hands.