It's from t-maps, and hourglasses do not tell the time. Hourglasses are just a countdown. The sand drains from the top half to the bottom half, and then the timer is done. It stops being useful in any way until you flip it over for the sand to drain again, in the same amount of time as before. I think it would be nice if they had an animation and/or function, but I would not expect it to tell me the time of day.
Yup no time, its a timer. It would be nice if it did spin the glass. And have sand fall. It is not interactive. It should be in some way.