John Snow mapped the cholera cases, representing each death as a bar.
His maps showed that many cases were clustered around a public water pump on Broad St. that was close to an old cesspit. The local council eventually disabled the pump by removing its handle.
The diagram below shows his original map overlaid by modern data points. The blue arrow points to the location of the pump.
Permeability id a scientific index of the soil to have air and water pass through the soil pore and spaces. As clay soils have a fine texture, with loamy soils moderately textured and sandy soils coarsely textured thus permeability changes from slow to rapid.
As sandy soil is highly permeable i.e 5.0 cm per hour and clay soils having the least i.e 0.05 permeability. Loamy soil is composed of sand, silt, and a smaller amount of clay.
From an agricultural perspective, the soil permeability depends upon the percentage of the see-page and the chemical makeup of the soil. Thus crops can grow more easily this type of soil as the particle size is minute and fine.
