This series consists of enrolments made up in the Petty Bag Office of specifications of patent inventions and surrenders of office.
Specifications, complete with drawings or sketches, give a description of the patented invention sufficiently full to enable its nature to be understood and applied in practice.
There is a huge range of subjects for patents in this series. Many involve industrial processes, and machinery for industry, and cover areas such as thread spinning, cloth weaving of all types, ironworking and other heavy engineering, railways, shipping, chemicals, paper making, brewing and distilling, refining and drying foodstuffs and oils, filtering and purifying water, and the manufacture of screws, locks, springs, bricks and tiles.
Processes and machinery for the improvement of agricultural methods are also well represented. There are specifications for many items of clothing, hosiery, furniture and furnishings, household articles of many varieties, and improvements to utilities and amenities, such as gas, water and paving.
Also represented are many famous names, particularly industrial engineers such as James Nasmyth, William Congreve, John Heathcoat and William Fairbairn, as well as John Dolland for optical inventions and Joseph and John Manton for gun making.
Certain surrenders of office are enrolled with the specifications, although the reason for this is not clear. They are few in number compared with the specifications, and tend to occur more in the early rolls. Examples of such offices include master in ordinary in the Court of Chancery, baron of the Exchequer, Oxford University professor, and the governor of Alderney.