1. A Mechanical Device: the sector compass Alfredo Rodriguez Department of Mathematical Sciences University of Texas at El Paso October 16, 2001

2. Outline Sector compass –Description of device –Different scales Lines of lines Lines of superficies –Application –Building your own sector compass

3. Sector Compass Introduction –Invented by Guidi Ubaldo de Monte –The device has different scales Lines of line Lines of superficies –The compass was used for about two centuries

4. Description of Sector Compass Given that AB=AC. If AE=AD, then AC and AB are cut proportionally. Draw in BC and DE AB:AD=BC:DE AB and AC are legs of sectors

5. Sector Compass

6. Scales of Line of Lines Each ruler has equally space marks starting from point A.

7. Application for the Sector Ruler using line of lines Increase a given line segment p by proportion of 3:5. Given a segment, p. Open rulers up until p fits into 3-3, then find 5-5 segment. This will be the desired length.

8. How tall is the chair? This artwork is outside of Denver Public Library. The horse is 7 ft tall.