Leonhard Euler was the leading eighteenth-century critic of Isaac Newton's projectile theory of light. Euler's main criticisms of Newton's views are surveyed, and also his alternative account according to which light is a wave motion propagated through the aether. Important changes are identified as having occurred between 1744 and 1746 in Euler's thinking about the way in which a wave such as he supposed light to be is propagated through a medium. Paradoxically, in view of Euler's overtly anti-Newtonian stand, these (...) amount to Euler abandoning his early, Malebranchian notions about the physical basis of wave propagation, in favour of the ideas set out by Newton in Book II of his Principia. (shrink)

I suggest in this article that Benjamin Franklin's electrical experiments were naturalistic and reactive towards providential theories of natural harmony and electricity provided by the English experimentalists Stephen Hales, William Watson and Benjamin Wilson. Conceptualizing nature as a divine balance, Franklin rejected English arguments for God's conservation of nature's harmony, suggesting instead that nature had within itself the ability to re-equilibrate when rendered unbalanced. Whilst Franklin's work reveals an experimentally defined fissure between providential and naturalistic views of matter and motion (...) in the mid-eighteenth century, his subsequent reflections on the use of natural philosophy sheds light on the divergent trajectory of utility implicit in these differing views. Hales and Watson in particular believed that insight into nature's providential manifestations gave the natural philosopher a medically restorative role, aligning the power of nature with God's benevolent purpose to heal the infirm. For Franklin, humanity behaved like nature, moving only when necessary. Natural philosophy existed to help these needs, making new worlds that had no dependence on God. (shrink)