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Many years ago while reading a C. S. forester book on the sailing adventures of Heratio Hornblower I came across an interesting word that I had to look up. It was a word meaning the air space remaining above the liquid in a barrel of the ships drinking water. I had a reason to use just such a word the other day to refer to the air space in a beer bottle. However, I couldn't dredge the word up from the depths of my memory. Does anyone know the word?
...was that is “wasted space”.
Maybe it is time for a physics lesson; that "wasted space" is required.
Most liquids are incompressible although they change volume as temperature changes. If the bottle was completely full and its temperature increased, the bottle could no longer contain the pressure and would break, spilling the contents :-(.
The ullage or headspace is made up of gas which is compressible and allows the liquid to expand or contract as necessary without putting undue stress on the bottle.
HTH. BTW, thanks for "ullage".
Emmett
Ullage isn't what's 'lost" in passage, it's how you measure what's used up. That is how you gauge your need to find fresh water if you are out on a large body of salt water in a boat and there aren't any motors or helicopters because it isn't the here and now. In times when your life depended on the accurate measurement of ullage, it was an important scientific measurement...especially if there wasn't any walking home if it was wrong. the more contemporary definition sprang into place after the advance of scientific studies of such things. Before that, it was a clear and defined observation of usage and evaporation hat was crucial to survival in an organized crossing out on the high seas, or maybe in a desert crossing. I remember seeing it in a museum collection near the Uffizi in Florence on some truly aged display of seafaring gear including sextants and astrolabes back in the 1970s.
Martha Barnette
Grant Barrett
Grant Barrett
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