Image of “clepsydra” (Ѻ); a presumed variation of built by Ctesibius (c.250BC).
In science, clepsydra, aka a “decanting vessel” (Grant, 1981), refers to []

The following are related quotes:

“As when a young girl, playing with a clepsydra of shining bronze, puts the passage of the pipe against her pretty hand and dunks it into the delicate body of silvery water, no liquid enters the vessel, but the bulk of air, pressing from inside on the close-set holes, keeps it out until she uncovers the compressed stream. But then when the air is leaving the water duly enters.”
Empedocles (c.450), On Nature and Purifications (Fragment #); cited by Don Lemons (2017) in Drawing Physics (pgs. 13-14) who thinks this is where Empedocles got the “air” as fourth element from [1]

“In the medieval literature on nature’s ‘abhorrence of a vacuum’, the two most popular demonstrations were the clepsydra and the separation of two plane surface.”
Edward Grant (1981), Much Ado About Nothing [2]

“The clepsydra, basically a decanting vessel, is characterized by a narrow, open neck and wide body with small holes at the bottom, which is the part first submerged into the liquid to be decanted, usually water or wine. When all the air in the vessel is expelled and released by the incoming rising water, the narrow orifice at the top is stopped up, usually by covering it with the thumb. Upon lifting the vessel from the water, one observes that the water remains in the now elevated clepsydra despite the expectation that it would fall through the tiny holes at the bottom. Already in the first half of the twelfth century, Adelard of Bath had not only described the clepsydra without naming it, but also attributed its seemingly 'magical behavior' to a natural 'affection' existing among the four elements that constituted the universe, an affection so powerful 'that as soon as one of them leaves its position, another immediately takes its place; nor is this again able to leave its position, until another which it regards with special affection is able to succeed it'.”
Edward Grant (1981), Much Ado About Nothing [2]

1. Lemons, Don. (2017). Drawing Physics: 2,600 Years of Discovery from Thales to Higgs (pgs. 13-14). MIT.
2. Grant, Edward. (1981). Much Ado About Nothing: Theories of Space and Vacuum from the Middle Ages to the Scientific Revolution (clepsydra, 7+ pgs, quote, pg. 83). Cambridge.

External links
Water clock (Clepsydra) – Wikipedia.

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