Above and beyond the large number of practical solutions for instruments and notations typically presented in his virtuoso draughtsman's manuscript (he was employed, for many years, in the aerospace industry, as a draughtsman while also managing his ranch in Chihuahua where he carried out experiments in corn and chenepod hybrids) and the huge variety of techniques he developed for generating new scales and systems with musically useful potential (see especially the articles on the "Marwa Pemutations" and the "Purvi Modulations" as well as his later work with sequences of intervals associated with patterns in Pascal's Triangle, the "meta-meantone", "meta-slendro", "meta-pelog" and "metal-mavila", in particular,) I believe one of his most valuable contributions was the "combination-product set" which built upon his insight that the "tonality diamond" of Partch (with a precedent in Novaro, a diamond was basically a harmonic series multiplied by its subharmonic mirror) was, at base, a selection of tones based on globally organizing the factors of the (just) intervals between them. While the diamonds tended, inevitably, to reinforce a single tonal center, the Combination-Product Sets tended instead to be locally tonal while globally centerless, rich in symmetrical intervallic structures, but also rich in the total varieties of relationships found relative to each tone, and all in a compact system of just intonation of, typically, 6, 20 or 70 tones in total. To some degree, one could find in such a rich system a compelling alternative to many contemporary atonal practices in 12-equal.
Wilson's idea of a scalar "moment of symmetry", in which a generating interval (a fifth, for example), within a given modulus (an octave, for example) at certain numbers of iterations creates a pattern of scale step symmetry in which the instances of the generator (and one closing, anomalous interval) each subtend the same number of scalar steps, appears to predate the notions of generated and well-formed scales familiar to many in the academic theoretical community.
Wilson's principle publications were made over many years in the informal journal of experimental music, Xenharmonikon. The composer Kraig Grady hosts a large archive of Wilson's manuscripts here: http://www.anaphoria.com/wilson.html A dissertation on Wilson's music-theoretical work by Terumi Narushima is now in press.
And this, too: Erv was a generous teacher and a friend. He had an amazing ear (I was once tuning some metal tubes in his workshop and, from time to time from up in his room, he would shout out the ratios of intervals as they were tuned up "135/128! 13/12! 64/45!") and a greater imagination for new tuning systems, keyboards, and notations that all came in families that propagated and mutated like those corn or quinoa hybrids. He taught with generosity, mostly at his dining table, with excursions, when necessary, to the metallophones and bamboo marimbas and refretted guitars and the wheezing old Scalatron in his living room, and always began by asking if the student had anything to teach him first.
