Various instruments were used to determine location and assist in the process of making maps. Direction, latitude, longitude, and time were all variables that needed to be determined. The instruments used for these purposes were very crude to begin with and became more sophisticated as time passed. In some cases the technology existed for a long time before it was applied to navigation and mapping, for example the compass. In other cases, new technologies had to be developed in order the solve a navigational problem, as in the case of determining the longitude. In still other cases, technology developed to improve the determination of one variable, was later appled to other purposes, such as the nonius.