John Horwood's skin was used to bind this book. The Latin inscription on its front cover reads 'Cutis Vera Johannis Horwood', which translates as 'the actual skin of John Horwood'. Surgeon Richard Smith carried out the dissection of John Horwood for a group of students in the Operation Room at the Bristol Infirmary. Smith described the process of tanning during an anatomy lecture:

the skin was undergoing the process of tanning in an adjoining tub - I received the materials and instructions for the process from the Sheriffs, both Tanners. The skin was also dressed at Bedminster, previously to being sent to Essex for the purpose of forming the covering of this book.

It contains notes collected by Smith on the trial as well as a sketches of Horwood and the bill for the binding of the book