Surveying is the process of measuring angles, altitudes and distances on land so that they can be accurately plotted on a map. Navigation is planning, directing, or plotting the position of a moving ship or other vehicle. The Maynooth collection is particularly rich in circumferentors, one of them (343 - dated 1688) being the oldest Irish signed instrument preserved in Ireland. Another highlight of the collection is the Heath theodolite (371) dating from about 1725.

The surveying and navigational instruments kept in the Museum can be divided into eight categories as follows:

	Circumferentors
	Clinometers
	Compasses
	Land Chains
	Levels
	Octants and Sextants
	Other Surveying Instruments

Circumferentors