John Desaguliers of Hart Hall, now Hertford College, in Oxford .
Of French Huguenot origin, he arrived in Islington as a small child. He later studied at Christ Church College in Oxford. He also lectured experimental philosophy at Hart Hall. Later he moved to London where he lectured on experimental philosophy at the Royal Society, at court, and in his own home.
One of Desaguliers’ lectures concerned Isaac Newton’s recently established three laws of motion. He also used a planetarium, or orrery, to visualise the motion of the heavenly bodies in our solar system according to the Copernican system. By turning a crank the planets and Earth are set in motion around the Sun.
This illustration shows how Desaguliers’ lecture on hydrostatics featured a number of different fountains. He also used narrow cylindrical jars filled with water containing hollow bubbles of glass, figures of men and a devil, and a hollow glass skeleton. These objects are filled with air and made to move within the jars by changing the pressure of the air.
Some principles of force could be demonstrated by performers or strongmen, as shown in the illustration below. Figure 4 shows a man using the force of a sledgehammer to hammer a piece of iron laid on the chest another man who is lying on his back. The author states that the larger the piece of iron laid on the man’s chest, the less the force of the strike is felt. It could then be revealed that it is not the strongmen who have a particular resistance to the heavy blows.