On Saturday 04 September 2010 20:49:33 Pat Naughtin wrote: > Dear John, > > In the definitions you report below, which inch applies? > > Is it now the 1960 (metric) inch set at 25.4 millimetres exactly? > > Is it the survey (metric) inch set at 1/36 of 36/39.37 of the > international prototype metre set in 1893?
The gallon is defined in terms of the 25.4 mm inch, even when using the survey foot to measure distance. However, the 6 ppm difference in volume between gallons defined by the two inches is dwarfed by other uncertainties. When a surveyor computes a volume, usually it's either dirt being moved or storm water flowing. Neither the packing ratio of the dirt nor the friction of water on ground is known with anywhere near that precision. Pierre -- When a barnacle settles down, its brain disintegrates. Já não percebe nada, já não percebe nada.
