 In 1842–1843, Robert Mayer and James Joule had formulated principles of the conservation of energy. Their work asserted the conservation of mv2, the mass of a particle times the square of its velocity. Further, Joule and Mayer argued that heat and mechanical work are interchangeable (see Kuhn 1969, Mach 1911). Helmholtz called on Joule’s work (though he claimed to be unaware of Meyer’s) to achieve three results. As Bevilaqua (1993) sums it up, Helmholtz concluded that that: