This encyclopedia investigates the historical development, technical construction, and cultural significance of the pipe organ as a musical instrument. The authors, Douglas Bush and Richard Kassel, compile extensive research to provide a comprehensive reference for scholars, performers, and enthusiasts. The text serves as a systematic examination of the instrument's evolution across various geographical regions and historical periods, utilizing a structured, encyclopedic framework to organize complex technical data.

Experts and musicologists recognize this volume as a foundational reference work for the study of organ history and mechanics. Readers frequently note the academic density of the prose, which makes it a highly reliable resource for specialized research and professional consultation.