The function of an Hourglass is to mark the passing of time as sand trickles through the narrow waist in the middle of the transparent glass container.  It is a very old Freemasonry symbol.  Many think the Egyptians use a clepsydra or water-clock and it was the predecessor of the hourglass.  I got news for them.  If it’s a Freemason and Alchemical symbol, it was used in ancient Egypt.  After all we get Hour from the name Horus.