The centerpiece of the Instrument Room is the large electrostatic generator built by John Cuthbertson in 1784. This apparatus is the largest flat-plate electrostatic generator of the world and the oldest piece in the room itself, which is filled mostly with items from the 19th century. Surrounding this centerpiece are 10 numbered cabinets filled with instruments accompanied by numbered cards that can be cross-referenced to a guide located in the room.