This is the first grouping of papers dedicated to Henry Cavendish's work in meteorology, focused on instruments and measurement. During the latter half of the eighteenth century, meteorological observations began to attract an increasing amount of attention. In 1773, the Royal Society instituted under Cavendish's superintendence and direction systematic and regular observations of atmospheric temperature, pressure, humidity, rainfall and wind, as well as on magnetic variation and inclination, at their house in Crane Court and subsequently at Somerset Place. A couple of years after the instruments were installed at Crane Court, Cavendish was tasked with examining their condition and mode of working, leading to his publication "An account of the meteorological instruments used at the Royal Society's house" (31 December 1776 Vol. 66) (Thorpe, Edward "The Scientific Papers of the Honourable Henry Cavendish" (1921; Cambridge, Cambridge University Press) Vol II p53). See also Jungnickel, Christa and McCormmach, Russell "Cavendish: The Experimental Life" (1999; Bucknell), pp220-4.
Some of these records may relate to Cavendish's work on the Society's instruments and his work calibrating and developing more accurate instruments of measurement.
HY/4/1-9 are concerned largely with Cavendish's testing of hygrometers (HY/4/5-HY/4/9). HY/4/10-20 relate to a variety of subjects, including Cavendish's testing of instruments and measuring of the temperature of wells. HY/4/21-24 relate to Cavendish's observations with various instruments. HY/4/30 contains Cavendish's notes on a barometer.