This hardback book is in very good condition. The shiny cover is in excellent condition, with a minimum amount of shelf wear. Internally the pages are in excellent condition - clean, tight and unmarked, with almost no sign of use. Like the earlier volume covering the nineteenth century this collection of patents registered at the British Patents Office is a valuable resource for anyone interested in theatre, engineering, magic, and architecture. It includes many fascinating developments relating to moving lights, projection, dimming and control, as well as staging, illusions, and a many other aspects of theatre technology. It reads like the Who's Who of entertainment manufacturing. Many famous names appear in the database including Stelmar, Siemens, Strand Electric, Furse & Co, Blau-Vogel, Holophane, Coliseum Syndicate, Hall Stage, Burkitt, British Thomson-Houston, Schwabe, Waagner-Biro, GEC, Kirby's Flying Ballet and even Frank Matcham!