It is simple and inexpensive to make a clock-accurate sundial, and superior to mass produced sundials. Sam Mullers modern sundial is an amazing scientific tool. By its shadow you cn read correct clock time, and also observe the effects of the earths tilt, rotation, and changing orbital speed. Then on a moonlit night from the shadow cast on your now "moondial" you will notice the moons counterclockwise orbit of the earth shows a small loss of time hour after hour, explaning why a lunar month is more than a day shorter than a solar month. During his long career as a science teacher and educator, Mr. Muller has inspired many young minds with the wonders of science.