In 1870 he became a lecturer on philology at Queen's College, Kingston, Ontario; and in 1881 he moved to Washington, D.C. at the suggestion of his son Graham, where he devoted himself to the education of the deaf by the use of Visible Speech in which the alphabetical characters of his linguistic invention were representative graphic diagrams for the various positions and motions of the lips, tongue, mouth, etc., as well as other methods of orthoepy.

[7] When the Duke and Duchess of Cornwall (later King George V and Queen Mary) called on Brantford for a visit, Melville was asked to greet the dignitaries at the public event.

[10] Melville's works on Visible Speech became highly notable, and were described by Édouard Séguin as being "...a greater invention than the telephone of his son, Alexander Graham Bell".

[12] Graham's scientific and statistical research work on deafness became so large that within the period of a few years his documentation engulfed an entire room of the Volta Laboratory in Melville's backyard carriage house.

Due to the limited space available at the carriage house, and with the assistance of Melville who contributed US$15,000 (approximately $510,000 in today's dollars),[13] Graham had his new Volta Bureau building constructed close by in 1893.