"with compasses and theodolites"
Theodolite - Credit: Rama
A theodolite is an instrument used in surveying and engineering. It can measure both horizontal and vertical angles. One of the first examples of a theodolite was built by Joshua Habermel in Germany in 1576. The theodolite replaced a similar, earlier instrument called a dioptra
which dated from the 3rd century BC and was used in astronomy.