The hourglass or sand timer is the oldest time telling machine. It is symmetric glass funnels through which the sand flow. The flow is adjusted in such a way that, it takes exactly an hour or so to make the upper glass empty of sand. Nowadays it does not have much practical use as we have modern time telling machines. It is mostly used as decor in the houses.
Australian Parliament still has about three sand glasses, its kept as memory the legacy from the colonial era.