INSTRUMENTATION FOR AN EARLY GEOLOGIST

The laboratory and field work of eighteenth century geologists was both thoughtful and accurate, as far as their instruments would allow. It is surprising just how much they would allow. Despite his reputation as a Mosaic geologist, a closer look at Richard Kirwan's (1733-1812) papers demonstrate why he was one of the most respected scientists of his day. His earlier reputation was as a chemist, but he was very influential in his geological work, partly founded on his laboratory investigation of the chemical and physical properties of minerals and rocks. His interests were still broader, and included duty as director of mines for Ireland as well as meticulous meteorological observations.

In his laboratories at the different places Kirwan lived, there were furnaces for varying degrees of heat, all appropriate glassware, balances, thermometers, ceramic vessels, and gas collection apparatus. He made use of a new and improved air pump to evacuate collection bottles for gases. Gases soluble in water were collected over mercury. He devised an aerometer that would register light winds directly, as well as allowing heavier winds to be measured with an indexed scale in pounds of force. His barometers were finely calibrated, by which he found a mathematical relation that allowed him to calculate differences in air temperature at different altitudes. Use of a hygrometer allowed him to calculate the effect of water vapor on the density of atmospheric air. He found specific gravities of solids, liquids, and gases with careful measurement and innovative calculations. He joined his conjectures about magnetism to his observations about affinity within and between substances. As well, Kirwan was knowledgeable about how to determine the dip of subsurface coal veins with information from properly placed borings. Knowledge of geological properties was much expanded with his work.