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.
In the unconfined aquifers, the water table is located at the outermost part of the aquifer. The water in the confined aquifer is usually the water that receives runoff, snowmelt etc. To keep it simple, unconfined aquifers have no confining layers. The confined aquifer has confining layers between the water level and the ground level. The water in this type of aquifer runs between two beds of impermeable layers. The final type of aquifer is known as the perched aquifer. Perched aquifers are aquifers that have no confining layer below the ground level and sit above the main water table., Figure 1 Schematic of confined and unconfined aquifers.