 Helmholtz knew of Euler’s and Lagrange’s previous mathematical formulas describing fluid motion. Euler’s equation treated fluids as continua or fields, whereas Lagrange’s formulation treats them as discrete particles (see Emanuel 2000, 8). Helmholtz took up Euler’s equation, which gives the equations of the flow of fluids in which friction does not alter the fluid’s motion significantly (the “inviscid” fluids). Lagrange had remarked that Euler’s equations did not work for “viscous” fluids, in which the fluid’s friction alters its movement, because Euler’s equations work only on the assumption of a general conservation law, and viscous forces are not conservative (Farge 2004, cf. Königsberger 1906, 167).