Hourglass

An hourglass is a device used to measure the passage of time. It comprises two glass bulbs connected vertically by a narrow neck that allows a regulated flow of a substance from the upper bulb to the lower one due to gravity. Typically, the upper and lower bulbs are symmetric.

The specific duration of time a given hourglass measures is determined by factors including the quantity and coarseness of the particulate matter and the neck width.

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Source: Wikipedia · Image: Wikimedia Commons · CC0

LEAFSTEEP

The art of tea — steep times, ratios, and the culture of the cup.

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