Besides group shots of a mix of instrument types, this ‘Special Exhibit’ includes a graphometer, invented around 1598, which consists of a semi-circle dial with two independently pivoting alidades, so the instrument can measure vertical angles as well as horizontal depending on how it is held. Graphometers usually incorporate a magnetic compass. Because of its simple, compact and portable design, the graphometer was popular with surveyors for over two centuries, preferred over the theodolite by the majority well into the 1800s; a two-telescope brass transit with a simple azimuth ring made in the late 1700s in Liege, Belgium. The instrument would be placed on a staff and one of the independently pivoting telescopes sighted on a stadia staff or other reference, the other scope rotated to back site in the opposite direction or to turn an angle; a sighting level with an open ended rectangular tube without lenses, rather with thin brass cross bars at the objective lens position, from the early-1800s, the bulls eye bubble and black paint are a later addition; and a Troughton & Simms brass theodolite with the scope riding on the vertical arc, c1840. Some of the instruments in these picture are shown in greater detail in the various sub-categories of surveying instruments that follow.