The British pint is about 20% larger than the American pint since the two systems are not compatible. Almost all other countries have standardized on the metric system, so the size of what may be called a pint varies depending on local custom.
It is usually measured by the depth (in mm) of the water layer that can enter the soil in one hour. An infiltration rate of 15 mm/hour means that a water layer of 15 mm on the soil surface, will take one hour to infiltrate. In dry soil, water infiltrates rapidly.
The infiltration rate of a soil is the velocity at which water can seep into it. It is commonly measured by the depth (in mm) of the water layer that the soil can absorb in an hour. An infiltration rate of 15 mm/hour means that a water layer of 15 mm on the surface of the soil, will take one hour to infiltrate (see fig. 33). Fig. 33. Soil with an infiltration rate of 15 mm/hour. A range of values for infiltration rates is given below: