English Music Theory.

a working manuscript in places, by an unidentified author, containing a scientific treatise on harmonies, intervals and musical theory, of twenty-two chapters, an "Adenda", musical tables, and about thirty pages of musical examples, notated on twelve staves per page ("Divers Melodys in the Various Modes"), written in a mid eighteenth-century hand in black ink,  with deletions and alterations, together with additional notes and calculations, some on letter paper inserted or bound in

166 pages in all, in a mid eighteenth-century copy-book, partly foliated (1-50), folio (37x 25cms), watermark of "LVG" under the crowned fleur-de-lys shield, with the counter-mark lettered "IV" [Churchill 406; Heawood 1808 or 1843], with a few additional papers bound in or loosely inserted, including an address-panel addressed to Mr Treaves, contemporary vellum boards, label to spine, inscriptions of provenance from James Kent, English provenance, [c.1750], some browning, particularly in the musical examples, binding breaking with a few leaves becoming loose

James Kent (1700-1776), composer and music collector, organist of Winchester Cathedral 1738-1774: inscribed on the front pastedown "Mr Kent at Mr Bryans near the Savoy Gate in the Strand/ Mr Kent Organist at Winchester/ The Carrier Inns at the Rose at Holboun Bridge".  Neither the manuscript nor the inscriptions are in the hand of Kent himself and seem to indicate only that the manuscript was sent to him.  James Kent was an important music collector: see A. Hyatt-King, Some British Collectors of Music (1964), p.91. 

Condition is described in the main body of the cataloguing, where appropriate
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The main foliated part of the volume includes sections on "Terms of Intervals, Their component Parts",  "Addition of Intervals" (Books 1, chapters 1-11), "Subtraction of Intervals" (Book 2, chapters 1-22), and the "Adenda" (with cues for it indicated in the margins of the main text).  This is followed by tables of Pythagorean calculations of scales ("Scala Maxima in Acumine [...in Gravitate]", etc) and copious musical examples titled "Divers Melodys in the Various Modes authentic & Plagal of the Enharmonic Gender, express'd in Ratio's", notated on systems of two or three staves each.  The manuscript is apparently dated near the end "1750"