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.
The boundaries of an aquifer are usually gradational into other aquifers, so that an aquifer can be part of an aquifer system. The top of an unconfined aquifer is the water table.A confined aquifer has at least one aquitard at its top and, if it is stacked with others, an aquitard at its base.figure 1. Click on image for larger view. Figure 1 shows an example of an aquifer system in the lower Portneuf River valley.he top of an unconfined aquifer is the water table. A confined aquifer has at least one aquitard at its top and, if it is stacked with others, an aquitard at its base. figure 1. Click on image for larger view. Figure 1 shows an example of an aquifer system in the lower Portneuf River valley.