There existed essentially two theories of light during the early nineteenth century: the particulate theory and the wave theory. This we realise today is a gross over-simplification, since there were many varieties of each theory. But to the supporters of one theory the other theory had faults so fundamental that no distinction between varieties of the same theory was sufficient to placate opposition to that theory. This meant that opponents of either the wave or the particulate theory seldom, in their (...) attacks, distinguished between different varieties of either theory. (shrink)

As a natural philosopher, Count Rumford is best known for his vehement advocacy of a motion or mechanical hypothesis of heat and for the dramatic experiments that he performed to support this hypothesis. Although a motion hypothesis which held that heat was merely the motion of the ultimate particles of a body had a distinguished history, with advocates that included Bacon, Boyle, Hooke, and Newton, most British natural philosophers by the beginning of the nineteenth century believed that the phenomena associated (...) with heat were caused by an imponderable fluid. William Henry reflected contemporary opinion in 1803, when he wrote:The former of these opinions [i.e. the existence of caloric], though far from being universally admitted, is now generally received; and the peculiar body, to which the phenomena of heat are referred, has been denominated by M. Lavoisier [as] caloric. (shrink)