INSTRUMENTS The Manual of Musical Instrument Conservation. By Stewart Pollens. Cambridge: Cambridge University Press, 2015. [ix, 448 p. ISBN 9781107077805 (hardcover), $150; ISBN 9781316309742 (e-book), $120.] Illustrations, tables, bibliography, index.Stewart Pollens is one of the leading authorities on the care of historical musical instruments, having served as musical instrument conservator at the Metropolitan Museum of Art from 1976 to 2006. Over the course of those three decades, he helped to preserve and restore their collection of over five thousand objects, including some of the world's most famous keyboard and bowed string instruments. his most recent book, The Manual of Musical Instrument Conservation, Pollens has distilled the wisdom and experience derived from his museum work, drawing on a shop notebook in which he recorded his daily work on the collection.The book is organized in the form of a dictionary, with 118 alphabetically-arranged entries, from Acoustics to Woodworking. The entries vary in length from a mere few lines in the case of entries for Gold and gold-plated brass and or Epoxy removal, to veritable articles spanning a dozen or more pages, on such topics as Historical metrology, Organ restoration, and Stringed-keyboard restoration. This is therefore not a book one would necessarily read from beginning to end, but the author provides both a convenient table of contents that includes all of the entry titles, and a detailed index, which can be used for finding matters that are discussed in multiple entries. Moreover, each entry ends with a list of references for further reading on the topic.This book will be useful to many categories of readers, not only the small population of professional conservators of musical instruments. Any museum professional will find Pollens's work valuable for dealing with myriad situations with which they may be confronted, from restringing a harp to moving a piano or cleaning a trumpet. Instrument builders will also benefit from Pollens's observations, especially if they repair historical instruments or make reproductions of such instruments. Finally, musicians who read this book will come away with a better understanding of the issues that concern the preservation of the tools of their trade.The concept of this book is highly original. It does not aim to replace any of the existing texts on the conservation of specific instrument types, such as keyboards or violins. Nor does the book attempt to present a deontological approach to instrument conservation, especially when it comes to the thorny question of whether historical instruments should be restored to playing condition. On this issue, Pollens writes, In general, I neither advocate nor disapprove of the restoration of historic musical instruments; rather I believe that each instrument and proposed treatment must be considered on a case-by-case basis with consideration given to the requirements and needs of the collection or owner (p. 2). The only work that resembles Pollens 's book is The Care of Historic Musical Instruments, edited by Robert L. Barclay (Edinburgh, Ottawa: Museums and Galleries Commission, Canadian Institute, 1997), but the differences in approach and emphases between Pollens, a string and keyboard specialist, and Barclay, a brass specialist, make for stimulating comparisons.The topics covered in the book range from general themes (Acoustics and Authentication) and philosophical or deontological issues (Ethics and Conservation reports) to more specialized subjects pertaining to the materiality of conservation (Benzotriazole, Bleach, Brass and bronze alloys, and Glues, pastes and other adhesives). …