Very nice. Practical: take a 15cm ruler and drill small holes at each end. Thread a 1.2m ish loop of string through the holes so there is a radius of 57cm. Tie

Very nice. Practical: take a 15cm ruler and drill small holes at each end. Thread a 1.2m ish loop of string through the holes so there is a radius of 57cm. Tie the string together about 20cm from the ruler. The result lets you measure angles on the horizon, e.g. width of Moon (not Sun with children please!) and the altitude of navigation stars near rise and set. http://en.wikipedia.org/wiki/Kamal_%28navigation%29 http://en.wikipedia.org/wiki/Kamal_%28navigation%29 http://kaloujm.com/page_kamal_uk.php http://kaloujm.com/page_kamal_uk.php