“And that we may not be decieved by false Notions which we have embraced without Examining, or that we have received upon the Authority of others; we ought to call in Question all such things as have an Appearance of Falshood, that by a new Examen we may be led to the Truth.”

Lectures of Experimental Philosophy…
John Theophilus Desaguliers (1683-1744)
London: Printed for W. Mears at the Lamb without Temple-Bar; B. Creake, at the Bible in Jermyn-Street, St. James’s; and J. Sackfield in Lincolns-Inn-Square, MDCCXIX (1719)

J. T. Desaguliers’ writings on mechanics were published as a set of lectures in 1717 in an 80-page tract of brief abstracts. This work, Lectures of Experimental Philosophy, edited by Desaguliers’ student, Paul Dawson, is believed to be spurious, published without consent of the author. Dawson, in his dedication, states that he had the author’s acknowledgement.

“I therefore humbly Present to You the following treatise, containing the several Philosophical Experiments in his publick Lectures, which I have carefully collected, and that Gentleman approved of.”

Desaguliers disavowed this, although he wrote in his Preface, or Advertisement to the Reader, that “he looked over the whole book and corrected every error.”

“Mr. Dawson (a young Man whom Sir Richard Steel had put under my Care) took a Copy of the Lectures above-mentioned, that they might be of Service to him when he went thro’ my Courses, and they were afterwards sold and published without my Knowledge. But as the Booksellers have made me Satisfaction, and purchased the Copy of me, I have looked over the whole Book, and corrected every Error therein…”

In any event, in this work Desaguliers tells the reader “How to make a heavy Body seem to rise it self,” “How to Condense the AIR, so that you may put what Quantity you please into a Vessel,” gives a “description of the Air-Pump Mr. Boyle made use of,” describes different types of barometers, thermometers, and hydrometers; and offers an essay on Isaac Newton’s “Colours.”

Desaguliers was born in France and raised in England. He studied at Oxford under John Keill, spending a good deal of his time reading Newton’s Principia. He attended a course of lectures given by s’Gravesande on mechanical consequences of the laws of motion as Newton defined them. In 1720, Desaguliers translated s’Gravesande’s work on Newton from Latin into English. As one of the foremost researchers in the Royal Society, he repeated several of Newton’s experiments on heat, optics and mechanics. Some of his results were made use of by Newton in the third edition of Principia. Desaguliers was an ardent supporter of Newton.

This is a reissue of A System of Experimental Philosophy, London, 1719.

The title-page is new, a preface by the author is added, an errata leaf and an advertisement leaf advertising the English translation of a work of Herman Boerhaave (1668-1738) have been prefixed to the original title page.

Rare Books copy bound in contemporary Cambridge binding, rebacked. Text contains a few contemporary annotations and an ownership signature of James (?) Hardy on the paste-down.