Lectures, 1780-ca. 1790

This series contains manuscripts of lectures Williams gave while Hollis Professor of Mathematics and Natural Philosophy at Harvard, from 1780 to 1788. Dates at the end of the lectures indicate that Williams delivered them more than once; many of the lectures were given on multiple occasions at Harvard and again during Williams' tenure as lecturer on natural philosophy and astronomy at the University of Vermont, from 1807 to 1809. The lectures were not solely given in college settings; annotations on some lectures indicate that they were first read in Boston, for a popular audience. Also included in this series are lectures Williams compiled for publication (folders 8 and 9). While he notes that these lectures had been read at Harvard while he was Hollis Professor, the date(s) on which they were read is not indicated. This series also includes a volume entitled Change of Climate in North America and Europe (folder 10); it is unknown if this was ever delivered as a lecture, and it appears likely that it was intended for publication. The topics of the lectures in this series are varied and include astronomy (sun spots, stars, the moon, lunar eclipses, comets, the galaxy), heat and cold, gravity, repulsion, pneumatics, gunpowder, magnetism, the heat of the Earth, the discovery of the planet Uranus, and global climate change and its causes.

It should be noted that the contents of the lectures are often more expansive than their titles might suggest. For example, the Lectures on Air (parts I and II) include information about the mechanical properties of air, including its fluidity, gravity, elasticity and transparency, and about Williams' classification of different "types" of air: common, fixed, nitrous, inflammable, marine acid, and alkaline. Although the format varies from one lecture to another, many include suggested experiments, related scientific history, and detailed personal observations. It is clear that Williams often conducted experiments as part of his lectures, to demonstrate firsthand to his students how the theoretical principles they were learning worked in practice. The influence of Enlightenment ideals regarding reason, science, and the pursuit of knowledge is evident in all of Williams' writings, and it is notable that Williams and his predecessor, John Winthrop, were largely responsible for an increased secularization of the sciences as they were taught at Harvard. Some of the lectures include charts and other data (including magnetic inclinations and average mean temperatures) from Europe, South America, New Zealand, and other locations across the globe. The lectures intended for publication include footnotes to indicate Williams' sources of information. Among the scientists and works he refers to or cites are Tycho Brahe, Sir Isaac Newton, Alexandre Guy Pingré, Jan Hendrik van Swinden, De Laland's (referred to as De La Lande) Astronomie, John Winthrop, Roger Long, Richard Watson's Chemical Essays, Robert Boyle, the Bible, Andrew Oliver's An Essay on Comets in Two Parts, David Gregory, Johannes Kepler, and Sir William Herschel (discoverer of the planet Uranus in 1781).