How did Henry Cavendish collect gases during his chemistry experiments?

Henry Cavendish collected gases during his chemistry experiments by using bottles inverted over either water or mercury.1

This method allowed him to isolate and study various "factitious airs," such as "inflammable air" (hydrogen) and "fixed air" (carbon dioxide), which he produced by dissolving metals or alkalis in acids. By using these collection techniques, Cavendish was able to perform rigorous quantitative experiments to measure the solubility, specific gravity, and combustibility of the gases he produced.1