In 1910, Whittaker wrote "A History of the Theories of Aether and Electricity", which gave a very detailed account of the aether theories from Rene Descartes to Hendrik Lorentz and Albert Einstein, including the contributions of Hermann Minkowski, and which made Whittaker a respected historian of science.
On the Partial Differential Equations of Mathematical Physics Paper on Scalar Potential - https://www.physicsforums.com/threads/whittaker-1904-paper-on-scalar-potential-functions.567056/
See Also
Bearden
Ether - Whittaker
Heaviside Component
Whittaker Structure