On the Correlation of Physical Forces

Sir William Robert Grove's work, On the Correlation of Physical Forces (1846), is recognized for enunciating the principle of the conservation of energy a year before Hermann von Helmholtz. This principle states that the total energy of an isolated system remains constant, even as energy transforms from one form to another. Grove, a British physicist, also built the first fuel cell in 1842. The concept of energy, defined as the capacity to do work, has evolved to include various forms such as kinetic, potential, thermal, chemical, and even mass-energy equivalence as described in relativity.1234