That Ruskin was as much on the alert in regard to this theory as he was in regard to Newton’s theory of gravitation, is shown by the following utterance from his The Queen of the Air. Obviously stirred by Tyndall’s newly published treatise, Heat as a Mode of Motion, Ruskin felt the need to criticize the endeavour of contemporary science ‘to simplify the various forms of energy more and more into modes of one force, or finally into mere motion, communicable in various states, but not destructible’, by declaring that he would himself ‘like better in order of thought³ to consider motion as a mode of heat than heat as a mode of motion’.