The following glossary of medical terms was assembled as part of a project on medicine from 1760-1830 but it includes some terms from a wider period. I have drawn on several sources, including, with the permission of the author, Medical Terms used in the late 18th Century which appeared on a now obsolete web site written my Melanie McClusky. Information from Dr Johnson's Dictionary, first published in 1755, is shown in red.
Figure 2 is a simple cartoon showing three different types of aquifers: confined, unconfined, and perched. Recharge zones are typically at higher altitudes but can occur wherever water enters an aquifer, such as from rain, snowmelt, river and reservoir leakage, or from irrigation.
An aquifer is a large body of permeable material where groundwater is present in the saturated zone. Good aquifers are those with high permeability such as poorly cemented sands, gravels, and sandstones or highly fractured rock.he rate at which groundwater moves through the saturated zone depends on the permeability of the rock and the hydraulic gradient. The hydraulic gradient is defined as the difference in elevation divided by the distance between two points on the water table.