premise: Over a temperature range from 25 to 200 * * f and at <mask> up to 250 atm , an overload of 300 psi , applied for a period of one day , results in an uncertainty in the pressure of , at most , one millimeter of mercury .
hypothesis: the proper context for <mask> here should be the force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit)