Yesterday morning, I tilted my little 1cm. square mirror so that the sunspot was located on the far north side of the ceiling. This maximized the projection distance (8 meters) and the size of the sunspot ellipse (20 cm. by 5 cm.) which also maximizes the velocity of the sunspot's movement. This maximizes the ceiling sundial's precision.
I was easily able to discern shadow movement in 5 seconds of time. The degree of precision is astounding! Since the ellipse was quite elongated, I found that it was easier to discern the movement of the little rounded edges of the ellipse's major axis (the pointed side) than it was to determine the center of the ellipse. Perhaps we should use the end of the major axis instead of the center when marking our dots on the ceiling. Now, I'm more convinced than ever that it would be nearly impossible to accurately construct a precision ceiling sundial using sundial generator programs and other layout aids. The connect the dot method is the only one that will not show errors. John John L. Carmichael Jr. Sundial Sculptures 925 E. Foothills Dr. Tucson Arizona 85718 USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Website: <http://www.sundialsculptures.com>
