Brief description

Precision measurement instrument used in surveying and engineering to measure angles in horizontal and vertical planes. It is essential for triangulation and precise mapping.

Use / Function

• Surveying: Mapping terrain, determining property boundaries.
• Construction: Aligning roads, tunnels, and building foundations.
• Geodesy: Measuring the Earth’s curvature through large networks of triangles.

Operating principle

Combines a telescope with two graduated circles (one horizontal and one vertical).

1. The operator points the telescope at point A and reads the angle.
2. Then points to point B and reads the new angle.
3. The difference is the angle between the two points. The telescope can rotate freely on both axes.

How to create it

1. Base: A stable tripod with leveling screws.
2. Mount: A vertical axis allowing horizontal rotation (azimuth).
3. Telescope: Mounted on a horizontal axis (elevation).
4. Graduated Circles: Metal or glass plates with very fine degree markings.
5. Spirit Levels: To ensure the instrument is perfectly horizontal.

Materials needed

• Essential: Brass or Aluminum (non-magnetic to not affect nearby compasses), Optical glass (lenses).
• Tools: Precision lathe, dividing engine to graduate circles.

Variants and improvements

• Total Station: Modern electronic version including a laser distance meter and computer.
• Transit: Robust American version where the telescope can be inverted completely.

Limits and risks

• Fragility: Lenses and axes are delicate; a knock can misalign it.
• Requires Tripod: Needs a firm and stable base.
• Atmosphere: Heat haze/refraction can distort vision over long distances.