I am reading H.T.H. Piaggio's "An Elementary Treatise on Differential Equations and their Applications", published 1920 originally; I have the 1952 edition.
The first chapter "Historical Introduction" goes:
"The geometrical interpretation [of differential equations] was given by Lagrange in 1774, but the theory in its present form was not given until much later by Cayley (1872) and M.J.M. Hill (1888)."
"These theories [of partial differential equations] still remain in an unfinished state; contributions have been made by Chrystal (1892) and Hill (1917)."
Who is this "M.J.M. Hill"? Piaggio cites him a few times during the course of the text, citing papers in Philosophical Transactions and Proceedings of the London Mathematical Society, etc., but I can't find anything more than his footprint in the journals.
Anyone with any information about him?