Precedents for Descartes’ little devils must be connected with the attempts to make devices to measure temperature. One of the first samples is reflected in plate 57. A hollow pierced fish and another one solid go up and down the glass of water according to temperature. Another attempt to make a thermoscope is the one that Schott (1657) ascribed to Magiotti wrongly –a device always closed and with no chance of exerting pressure. Something similar is shown by Father Lana (1686). Sturm (plate 59) reflects the Florentine Experiment, which works like a thermoscope, and the Stutgardian Experiment, which does like a thermobaroscope. A similar illustration is shown by Leopold (1727).
Stocchetti (1705) uses a little devil to show the hydrostatic pressure effect on it, when water level in the container increases.
‘sGravesande, a Dutchman, places the container with little devils in a bell and increases pressure by putting air in it.
The Segner Turbine (1750) is regarded as the first hydraulic machine with an efficient vertical shaft. Its designer was inspired by the Cartesian little devil and its turn caused by draining water through the twisted tail.
Péclet (1847) depicts a classic little devil, but it is ballasted in a very precise way. Ganot (1866) achieves similar precision when exerting pressure with a piston at the top, which allows to be very sensitive and to keep the little devil at different heights indefinitely.
The little devil depicted by Meiser and Mertig (1891) allows water inlet inside the assembly to be watched more clearly.
Llinderstrom-Lang (1937) began to use little devils in order to calculate the quantity of oxygen consumed by several cells in their reproduction, depending on the pressure needed to return the devil to its initial level. This author was followed by Zeuthen (1947), and others who changed the machines, but they kept using little devils.