The Compass Two thousand years ago the Chinese had already developed a working compass. A piece of lodestone would be cut into the shape of a ladle . Placed on a stone board with a smooth surface, the lodestone would move round until the handle of the ladle pointed south while the bulk of the ladle was attracted to magnetic north. This interestingly shaped device is mentioned in a book from about A.D. 80. Other ancient books may have dated it as far back as the fourth century B.C. Jade finders played an important role in the invention of the ladle. They travelled great distances to look for jade. In order not to lose directions, they would take a ladle with them. However, the making of a ladle was a tough job. Much work needed to shape a piece of lodestone into a ladle would mean much of its natural magnetism had been lost. This again meant that only a few ladles could have been produced. Small numbers of ladles produced and growing need for navigation led to a search for ways to produce more compasses, and at the same time, smaller and better compasses. A Columbus was a great sailor and discoverer. C The invention of the compass is important in human history.
人教PEP[2013]版四上《Unit 1 My Classroom》(read listen and chant PartA Flash)flash课件
人教PEP[2013]版四上《Unit 2 My Schoolbag》ppt课件
人教PEP版英语四上《Unit 5 What Would you like》 Part B Read and write PPT课件
人教PEP[2013]版四上《Unit 2 My Schoolbag》(let’s sing PartB)flash课件
人教PEP[2013]版四上《Unit 4 My Home》(listen and tick or cross PartB)flash课件
人教PEP[2013]版四上《Unit 2 My Schoolbag》(let’s do)flash课件
人教PEP[2013]版四上《Unit 4 My Home》(listen circle and say)flash课件
人教PEP[2013]版四上《Unit 1 My Classroom》(第4课时)ppt课件
人教PEP[2013]版四上《Unit 4 My Home》(let’s do)flash课件
人教PEP[2013]版四上《Unit 1 My Classroom》(第3课时)ppt课件
人教PEP[2013]版四上《Unit 1 My Classroom》(story time)flash课件
人教PEP[2013]版四上《Unit 4 My Home》(let’s learn)flash课件
人教PEP[2013]版四上《Unit 4 My Home》(let’s talk)flash课件
人教PEP[2013]版四上《Unit 2 My Schoolbag》(let’s learn)flash课件
人教PEP[2013]版四上《Unit 1 My Classroom》(let’s talk PartA)flash课件
人教PEP[2013]版四上《Unit 1 My Classroom》(第1课时)ppt课件
人教PEP[2013]版四上《Unit 2 My Schoolbag》(read listen and chant)flash课件
人教版PEP英语四上2013版Unit 1
人教PEP[2013]版四上《Unit 1 My Classroom》(let’s sing Part B)flash课件
人教PEP[2013]版四上《Unit 2 My Schoolbag》(main)flash课件
人教PEP[2013]版四上《Unit 4 My Home》(let’s talk PartB)flash课件
人教PEP[2013]版四上《Unit 1 My Classroom》(read listen and tick PartA)flash课件
人教PEP[2013]版四上《Unit 2 My Schoolbag》(read and circle PartB)flash课件
人教PEP[2013]版四上《Unit 1 My Classroom》(第2课时)ppt课件
人教版PEP英语四上2013版Unit 3
人教PEP[2013]版四上《Unit 1 My Classroom》(课文朗读)flash课件
人教版PEP英语四上2013版Recycle 2
人教PEP版英语四上《Unit 4 My Home 》PPT课件之一
人教PEP[2013]版四上《Unit 1 My Classroom》(第6课时)ppt课件
人教PEP版英语四上《Unit 4 My Home 》第一课时PPT课件
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