The hourglass is a classic symbol that measures time until the sand runs out. This is a perfect allegory for life and death.
The hourglass is often seen on gravestones in conjunction with a skull and crossed bones which is symbolic of crucifixion, death, and mortality.
Winged hourglasses signify the resurrection of the dead. It can also be indicative of ‘tempus fugit’ meaning time flies.
A reclining hour glass does not allow the sand to pass indicating that time stopped prematurely. It is therefore symbolic of the death of a young person.
The headstones below contain a winged hourglass, and the image of a snake eating its tail (called ouroboros) representing everlasting life.
In this last instance the hourglass symbol is an integral part of the membership badge of the American Institute of Industrial Engineers.