Early efforts to build a thermometer
Scientists in the early 1800s wrestled with the problem of measuring temperature, often using brandy in a glass tube. It was a time when they did not understand what caused heat, and the idea that temperature was a measure of the speed with which atoms move was flatly rejected by London’s Royal Society:
“Early efforts at measuring temperature were purely empirical. However, exhaustive comparisons in the 1840s by French scientist Henri Victor Regnault showed that an ‘air thermometer’ — which measures changes in pressure of dry air in a sealed container — was superior to both in its reproducibility and designs of air thermometer calibrated at the freezing and boiling points of water gave consistent estimates of temperatures.
Source: delanceyplace.com