In human history to date, only a few species of large animal have been domesticated. In approximate order of their earliest domestication these are: dog, sheep, goat, pig, ox, yak, reindeer, water buffalo, horse, donkey, llama, alpaca, Bactrian camel and Arabian camel.
For instance at sea level and standard weather (29.9 Hg) a gauge vacuum of -25.9 Hg is equivalent to an absolute pressure of 4 Hg. In other words, the vacuum gauges that read, for example, -25.9 Hg at full vacuum is actually reporting 4 Hg, or 136 mbar. That is still in the low vacuum range.
Atmospheric and Gauge Pressure. 1  Absolute pressure: The total pressure exerted on a system referenced to zero Pascals, and equal to the gauge pressure plus atmospheric pressure. 2  Gauge Pressure: Pressure referenced to one atmosphere, and is the pressure actually shown on the dial of a gauge that registers pressure relative to atmospheric pressure. For example, an ordinary pressure gauge reading of zero does not mean there is no pressure, it means there is no pressure in excess of atmospheric pressure.