Published around 1200 AD, this book is a "things for a court engineer to make and do" for Arab engineers. If your patron needs a new mechanical diversion, or a more impressive water clock, which tells the hours by beheading a model prisoner, or a combination lock, or a machine for recovering items lost down wells, look no further. This amazing book has instructions for all these marvels, illustrated in copious details, even going into details of the mechanical processes involved.

I've got a spare copy, offers above $150 considered.

Absolutely amazing to consider what the West was up to technologicaly speaking at this time: hardly anything, the Dark Ages was in full swing, and Italy had yet to be chosen to host the Renaissance.