The University of Penssylvania has just recently acquired over fifty manuscripts from Ralph George Algernon Percy, the 12th Duke of Northumberland. The collection includes many volumes of interest to the esoteric-minded.
A portion of the collection is comprised of texts copied or acquired by Rainsford from the Jesuit College at Naples at its dissolution in the late 18th century. Other particularly notable items include an illustrated book on summoning demons, an astrological horoscope of King George III, a manual by Rainsford – written during his time as Governor of Gibraltar – on judicial astrology, and several alchemical notebooks used by Rainsford for commonplacing, or note-taking, on useful information and discoveries.