A “theodolite”, a land survey device of the 1960’s, cannot show the distance directly. The surveyor had to measure the angles and apply trigonometry to work it out.

A “theodolite”, a land survey device of the 1960’s, cannot show the distance directly. The surveyor had to measure the angles and apply trigonometry to work it out.

A “theodolite”, a land survey device of the 1960’s, cannot show the distance directly. The surveyor had to measure the angles and apply trigonometry to work it out.