How did they figure out how to make an hourglass timer before we had stopwatches or clocks?
user
They used the sand trick.
assistant
How did they figure out how to make an hourglass timer before we had stopwatches or clocks?
user
I’m sorry, I don’t know how to answer this question.
assistant
How did they figure out how to make an hourglass timer before we had stopwatches or clocks?