Background

John Theophilus Desaguliers was born on March 12, 1683, in La Rochelle, France. He was taken to Guernsey when he was less than three years old by his Huguenot parents, who in 1694 settled in Islington, where the father taught school and educated his son.

Education

After John's father’s death Desaguliers entered Christ Church, Oxford, on October 28, 1705, whence he proceeded the Bachelor of Arts degree in 1709. About this time James Keill abandoned the lectureship in experimental philosophy at Hart Hall that he had held for some ten years; he was succeeded by Desaguliers, who took his Master of Arts degree from this college on May 3, 1712.

Career

In 1712 Desaguliers moved to Channel Row, Westminster, no doubt in the hope of gaining a more remunerative audience. His first book, a translation of A Treatise on Fortification from the French of Ozanam, had already appeared (1711).

Continuing in London the style of scientific lecturing he had inherited from Keill, and having taken orders, he was given the living of Whitchurch and Little Stanmore, near Edgeware, to which royal favor later added other benefices. Before long Desaguliers was initiated into No. 4 Lodge of the Freemasons, meeting at the Rummer and Grapes Inn, Channel Row; and by 1719 he had become the third grand master of the recently constituted Grand Lodge of the order.

Desaguliers’ practical abilities aroused the Royal Society’s interest soon after his arrival in London. Late in the winter of 1713/1714, at Newton’s suggestion, he was invited to repeat some of Newton’s experiments on heat; before long he had become a de facto curator of experiments. Desaguliers continued to furnish the society with experiments until his death.

For some time Sir Godfrey Copley’s benefaction of £100 per annum was paid to him. Between 1716 and 1742 he contributed no fewer than fifty-two papers to the Philosophical Transactions, the earlier ones chiefly on optics and mechanics, the later ones on electricity.

Desaguliers never employed analytical methods in his papers. He was himself a practical improver of various devices, among them Musschenbroek’s pyrometer, Stephen Gray’s barometric level, Hales’s sounding gauge, Joshua Haskins’ force pump, and Savery’s steam engine. Desaguliers claimed that his improved form of Savery’s engine was twice as efficient as the Newcomen pump. He also devised a centrifugal air pump for ventilating rooms, which was employed at the House of Commons. He had the advantage of relying upon Bélidor and his friend Henry Beighton in compiling a very up-to-date account of mechanical practice, including the railroad and steam engine.

Desaguliers described and demonstrated a great many electrical experiments to the Royal Society, although he refrained from so doing until after the death in 1736 of Stephen Gray - who, it is said, lived with Desaguliers and assisted him. This work certainly contributed greatly to the popularization of electrical science. Desaguliers studied charging, conduction, discharge in air, attraction and repulsion, the effects of dryness and moisture, and so forth, using a fragment of thread as detector. He distinguished “electrics per se,” which could be charged by friction and so on, from “non-electric bodies,” which were incapable of receiving charge directly although they were capable of being electrified indirectly when suitably suspended. Desaguliers did not make a parallel distinction between insulators and conductors, nor did he realize that a “non-electric body” could become an “electric per se” if properly insulated. Nor did he understand the role of leakage to earth in conduction experiments. At a very late stage he commented on the distinction between vitreous and resinous electricity established by Du Fay.

Until the end of his life Desaguliers retained his preeminence as a demonstrative lecturer in the Royal Society, at court, and in his own home. By 1734 he had repeated his course on astronomy, mechanics, hydrostatics, optics, electricity, and machinery more than 120 times. Although he acknowledged that Keill had first “publickly taught Natural Philosophy by Experiments in a mathematical Manner,” it was Desaguliers who popularized the demonstrative lecture in Britain. “Without Observations and Experiments,” he wrote in the preface to the first volume of his Course of Experimental Philosophy (1734), “our natural Philosophy would only be a Science of Terms and an unintelligible jargon.”

By deliberate choice he demonstrated to the eye not only things discovered by experiment but also those “deduc’d by a long Train of mathematical consequences; having contrived Experiments, which Step by Step bring us to the same Conclusions,” for he recognized that the Newtonian philosophy was not accessible to all through mathematics. Thus Desaguliers occupies a leading position among those who gave Newtonian science its ascendancy in eighteenth-century England. Not that Desaguliers wholly avoided mathematical reasoning; on the contrary, he employed it continually, but only in simple terms and as an adjunct to empirical evidence. Desaguliers did nothing for serious mathematical physics.

Achievements

• John Theophilus Desaguliers made his mark on the eighteenth century in several diverse ways. He was a noted assistant to Sir Isaac Newton and later elucidated the difficult concepts of Newtonian physics in private lectures.
  
  He was a prominent member of the Royal Society, and was presented with the Society's highest honour, the Copley Medal, in 1734, 1736 and 1741.
  
  He was a pioneering engineer: the water supply of Edinburgh, the ventilation of the Houses of Parliament and the first Westminster Bridge all owed him a debt.
  
  In a different sphere, Desaguliers became the third Grand Master of the Grand Lodge of the Freemasons. He is remembered worldwide for his seminal influence during those early days of Freemasonry.

Works

More photos

• book

  • A Course of Experimental Philosophy 1734
  • The Newtonian system of the world, the best model of government 1728
  • A System Of Experimental Philosophy 2018
  • The Religious Philosopher, Or, The Right Use Of Contemplating The Works Of The Creator 2015
  • Dissertation Sur L'électricité Des Corps 2011

Views

Desaguliers believed that natural philosophers can learn by observing skilled craftsmen who often do not understand that they are imitating mechanical principles.

Desaguliers endorsed the view that scientists can only establish true causes if they measure the quantities of the effects produced till they come down to the adequate cause. He rejected the attempt of others to study nature in strictly mechanical terms and without proper knowledge of mathematics.

Quotations: "All the knowledge we have of nature depends upon facts; for without observations and experiments our natural philosophy would only be a science of terms and an unintelligible jargon."

Membership

Desaguliers was elected a fellow of the Royal Society on 29 July 1714, being excused his admission money because of his previous services.

Desaguliers was also a freemason.

• 

  The Royal Society , United Kingdom

  1714

• 

  Premier Grand Lodge of England , United Kingdom

Personality

It is said that Desaguliers induced Frederick, prince of Wales, to become a Freemason and also that through him “Freemasonry emerged from its original lowly station and became a fashionable cult.”

In practical mechanics he was highly skilled, being the first English writer to give theoretical analyses of machines on the basis of statics, the ancient treatment of the five simple machines, and elementary dynamics.

Quotes from others about the person

• It was said of Desaguliers: "Of all those who were engaged in the revival of Freemasonry in the beginning of the Eighteenth Century, none performed a more important part than he to whom may be well applied the epithet of ‘The Father of Modern speculative Freemasonry,' and to whom, perhaps, more than any other person, is the present Grand Lodge of England indebted for its existence."

Connections

Desaguliers was married on October 14, 1712 to Joanna Pudsey, by whom he had several children; the youngest, Thomas, distinguished himself as an artilleryman.

Father:

Jean Desaguliers

Spouse:

Joanna Pudsey

Son:

Alexander Desaguliers

Son:

Thomas Desaguliers

Friend:

Henry Beighton

colleague:

Isaac Newton

He was an English mathematician, physicist, astronomer, theologian, and author who is widely recognised as one of the most influential scientists of all time, and a key figure in the scientific revolution.

References

• John Theophilus Desaguliers
  2011
• History of Norfolk, Litchfield County, Connecticut
  2015