The study of the properties of air, pneumatics, was an important part of teachings in experimental philosophy. The air pump could be the most expensive piece of equipment in the demonstrator’s possession. The air pump was used to show the effect of the evacuation of air on substances and also on animals and insects.
Willem Jacob ‘s Gravesande (1688-1742): Mathematical Elements of Natural Philosophy Confirm’d by Experiments, 1726
The plate here shows experiments on air. Figure 1 represents a glass filled with air and immersed in water, illustrating the principle of a diving bell. Figure 2 shows “Cartesian devils”, glass figures filled with air, being made to travel up and down a cylinder by changing the pressure. Figures 3 to 5 show experiments on animals in glass jars: a bird, a rabbit, and fish. The animals cannot live if the air is withdrawn with the air pump.
Joseph Aignan Sigaud de la Fond: Description et usage d’un Cabinet de Physique Experimentale, 1775, vol. 2
This author also suggests an experiment (Figure 5) in which a bird is placed under a bell jar and the air is evacuated with an air pump. This demonstrates the importance of air for breathing. The text describes how the bird first finds it difficult to breathe, then convulses, and finally perishes.