Measuring coordinates Direct measurement( OK for graph paper) Triangulation Snell 1600s: Measure angles of triangles and one-distance in base triangle Distance measured with calibrated chain"or steel band(about 100 meters long) Baseline was about 1 km long Triangles can build from small to larges ones Technique used until 1950s 02/11/02 12.540Lec0202/11/02 12.540 Lec 02 5 Measuring coordinates • Direct measurement (OK for graph paper) • Triangulation: Snell 1600s: Measure angles of triangles and one-distance in base triangle • Distance measured with calibrated “chain” or steel band (about 100 meters long) • “Baseline” was about 1 km long • Triangles can build from small to larges ones. • Technique used until 1950s