I THE STORY OF EUCLID. PARTS OF A CIRCLE Of course there is no such person as Mr. Geometry. That is only the name given to what he can do, and the word itself is simply the Greek for "I measure the Earth." It means you can really do wonderful things if you can understand Geometry. Although there was no such person as Mr. Geometry, there was a very clever man, called Euclid, who wrote books about Geometry, and it is from these books that we have learnt what we know about this wonderful subject. Euclid was a Greek, who lived in Alexandria about 300 years B.C. As I said before, he wrote Books, which he called " Elements," and people who learn Geometry really make use of twelve of these books. Euclid is supposed to have written a great many more than twelve "Elements," but the rest were lost. What do you think became of them? Mrs. Euclid burnt them! She did not approve of her husband always poring over his work, and perhaps not taking enough notice of her. So, one day, she seized some of this "Elements," and made a bonfire of them. I know some people who have been heard to say, "What a pity she didn't burn the lot! But, of course, you don't belong to that set. One of the most important things to learn in Geometry is how to draw a circle (or describe a circle, as Euclid would say). With a pair of compasses practise drawing a circle. Be very careful to hold the compasses by the knob at the top, and never let your finger rest on the leg, or it may shift, and spoil your circle. Remember this: The middle point of a circle is called the Centre. The line round the edge of the circle is called the Circumference. Any part of the Circumference of a circle is called an Arc. A line drawn right across the circle is called the Diameter. A line drawn from the centre to the circumference of a circle is called a Radius. In Geometry you can use these signs, for short: O for Circle, O for Circumference. Describe a circle, any size you like. In it draw a radius, a diameter, and put their names |