Intended as a supplement to The Mechanical Muse: The Piano, Pianism and Piano Music, c.1760-1850, this Companion provides additional information which, largely for reasons of space but also of continuity, it was not possible or desirable to include in that volume. The book is laid out alphabetically and full biographical entries are provided for all musical figures mentioned, including composers, performers, theoreticians and teachers, as well as piano makers and publishers of music, within the period covered by The Mechanical Muse. There are also entries on figures of importance from outside the period but whose influence is palpably important within it, such as J.S. Bach. As well as biographical information, all these entries contain lists of principal works and a section on further reading so that readers can follow up people and matters of particular interest. Also included in The Companion are entries devoted to particular works and other information of relevance, such as descriptions of musical forms, characteristics of dances and so on, as well as some technical information on music and explanations of technical terms pertaining to keyboard instruments themselves and to ways of playing them. This Companion is not intended to replace existing reference books such as Grove or Musik in Geschichte und Gegenwart, but will be useful for those who desire to know more about a particular topic and do not necessarily have access to more specialist reference works, or time to visit large or specialist libraries. As such it is indispensable to users of The Mechanical Muse.