Experiment

The fortunes of experimentation in the eighteenth century were closely linked with the spread of Newtonianism. Opticks functioned as a model of a developing experimental tradition. Prominent representatives of that tradition were the Dutch Newtonians Willem Jacob's Gravesande (1688–1742) and Petrus van Musschenbroek (1692–1761), who wrote very influential books, whose main function was educational.

In the first half of the eighteenth century there was still no clear distinction between professional and amateur experimental philosophers. It was customary for experimentalists to obtain part of their income by performing striking electrical or optical experiments in public. This aspect of experimentation enlarged the audience for natural philosophy. However, it annoyed some university professors, who observed with dismay that the popularity of experiments was based on their potential for entertainment.

Experimentation for most of the eighteenth century was predominantly empirical and qualitative, without systematic guidance by mathematically formulated theories. Various phenomena (electrical, thermal, and chemical) were explored experimentally, on the assumption that they were manifestations of hidden imponderable entities (electric fluids, caloric, and phlogiston, respectively). The invention of new instruments (for example, the Leyden jar), and the improvement of existing ones (such as the thermometer), played a seminal role in investigating these phenomena. Earlier in the century the acquisition of instruments was the responsibility of well-off professors of experimental physics, who collected and stored them in "physical cabinets." In the second half of the century the task of establishing and maintaining collections of instruments was gradually taken over by universities and scientific academies.

Toward the end of the century, and especially in France, there was a shift toward the quantification of experimental physics. New quantifiable concepts were introduced, such as charge and heat capacity, which facilitated this shift and led to the construction of mathematical theories of static electricity and heat. Furthermore, precise measurements were systematically carried out and meticulously reported in numerical tables. Precision measurement gradually became a central preoccupation of experimental physics.