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1、Reading2021/8/11 星期三1The four basic instruments for navigation:Sinan,Inch Astrolabe,Sextant and nautical map.Sinan,the ancient Chinese compass.2021/8/11 星期三2It was invented by Zhang Heng in the It was invented by Zhang Heng in the Han dynasty.It is made up of a Han dynasty.It is made up of a bronze
2、foundation(bronze foundation(青铜地盘青铜地盘青铜地盘青铜地盘)and)and magnetic spoon(magnetic spoon(磁勺磁勺磁勺磁勺)which is made)which is made of natural magnet,positioned right in of natural magnet,positioned right in the central of the foundation.the central of the foundation.2021/8/11 星期三3The handle of the spoon point
3、s to the south,while the other side points to the north.When the Sinan is in the still,the handle of the spoon points to the south because of influence of the terrestrial magnetism(地磁地磁).2021/8/11 星期三4 It has 17 stars listed as well as a map of the sky overhead (for 37 degrees)and the ecliptic(黄道黄道)
4、.The time of day or night is on the outside edge with noon at the top of the Astrolabe and midnight at the bottom.It comes with a carrying chain,a pouch,and a book on its use.The reverse side has a sight for measuring the elevations of the heavenly bodies.astrolabeastrolabe2021/8/11 星期三5sextant2021/
5、8/11 星期三6The sextantThe sextant is a navigational is a navigational instrument for measuring the angle instrument for measuring the angle between the horizon and some object between the horizon and some object in the sky.First a sailor looks at the in the sky.First a sailor looks at the horizon thro
6、ugh an eyepiece.At the horizon through an eyepiece.At the same time he can see light from the same time he can see light from the sun or a star reflected off a small sun or a star reflected off a small mirror on top of the instrument,onto mirror on top of the instrument,onto a second mirror and into
7、 the a second mirror and into the eyepiece.eyepiece.2021/8/11 星期三7The navigator can then see two images,The navigator can then see two images,the horizon and the sun side by side.He the horizon and the sun side by side.He can then measure the angle between can then measure the angle between them on
8、a scale at the bottom of the them on a scale at the bottom of the instrument.The scale goes from 0 to instrument.The scale goes from 0 to 120 degrees.An earlier instrument,120 degrees.An earlier instrument,called a quadrant,measured in angle in called a quadrant,measured in angle in the same way but
9、 it could only measure the same way but it could only measure angles from 0 to 90 degrees.angles from 0 to 90 degrees.2021/8/11 星期三8nautical chartnautical chart2021/8/11 星期三9Nautical chartsNautical charts are maps of the depth are maps of the depth of the sea and the currents of the of the sea and t
10、he currents of the oceans.They provide modern sailors oceans.They provide modern sailors with routes through the seas,rather with routes through the seas,rather like roads through the countryside.like roads through the countryside.The information began to be The information began to be collected in
11、the nineteenth century collected in the nineteenth century and has continued to be updated ever and has continued to be updated ever since.These charts were not available since.These charts were not available to Captain Bligh or Zheng He.to Captain Bligh or Zheng He.2021/8/11 星期三10Discuss1.How do yo
12、u think seamen found their 1.How do you think seamen found their way before modern accurate methods of way before modern accurate methods of navigation were invented?navigation were invented?Kept close to the shore,used nature such Kept close to the shore,used nature such as the sun,wind,birds,tide,
13、etc,to help as the sun,wind,birds,tide,etc,to help them,and used some of the instruments them,and used some of the instruments including a compass,astrolabe,etc.including a compass,astrolabe,etc.2021/8/11 星期三112.Which do you think was easier to work out:latitude or longitude?Latitude,because it was
14、used to measure how far you had traveled from land on a straight line.It was discovered a long time before longitude.2021/8/11 星期三123.Can you identify these early navigational instruments seamen used and explain how they are used?1)compass(in ancient China)2)astrolabe3)sextant4)sea/nautical/marine c
15、hart2021/8/11 星期三134.Which ones do you think are still used 4.Which ones do you think are still used today?today?Sea charts are still used today.Sea charts are still used today.2021/8/11 星期三141.Where do these materials come from?2.What did the early navigator use to help them navigate?3.What natural
16、 objects were used to assist the navigation?4.Is it easier to measure longitude or latitude?5.Do the astrolabe,the quadrant and the sextant mean the same thing?Read and answer these questions.2021/8/11 星期三15Comprehending1.Read the passage and answer the following questions.1)What is the use of a bea
17、ring circle,astrolabe,quadrant or sextant?()What is the use of a compass?()A.To set the course of the ship B.To measure the position of the ship C.To measure the speed of the ship D.To tell the timeAB2021/8/11 星期三162)Why are speed and time important in 2)Why are speed and time important in working o
18、ut the longitude of a ship?working out the longitude of a ship?Speed and time are important in finding Speed and time are important in finding out the longitude of a ship because the out the longitude of a ship because the earth moves fifteen degrees westwards earth moves fifteen degrees westwards e
19、very hour.If you know your direction,every hour.If you know your direction,speed and time,you can work out the speed and time,you can work out the approximate longitude or change in your approximate longitude or change in your position in relation to the stars.position in relation to the stars.2021/
20、8/11 星期三173)Why is the position of the sun and various 3)Why is the position of the sun and various stars useful for working out latitude?stars useful for working out latitude?The position of the sun and stars are The position of the sun and stars are useful for working out latitude because useful f
21、or working out latitude because they are fixed points in the sky and their they are fixed points in the sky and their movements in relation to the earth are movements in relation to the earth are already known.So they can be used to already known.So they can be used to measure a ships position.measu
22、re a ships position.2021/8/11 星期三182.Suppose you were a sea captain aiming 2.Suppose you were a sea captain aiming to sail round Africa.Discuss in groups:to sail round Africa.Discuss in groups:1)What skills would you seek in your 1)What skills would you seek in your sailors?sailors?2)What problems w
23、ould you anticipate for 2)What problems would you anticipate for this journey?this journey?2021/8/11 星期三19What would you do if:Plan of actionYou were far from land and a storm arose.Wait till the storm is over,and then find your new position and return to your original course.3.Read the chart below
24、and fill in your plans of action to deal with them.2021/8/11 星期三20What would you do if:Plan of actionYou knew your latitude but didnt know your longitude.Use knots to find your speed and work out your approximate longitude.2021/8/11 星期三21What would you do if:Plan of actionYou were blown offcourse.Us
25、e the compass and the astrolabe,quadrant or sextant to find out your position,return to your former course.2021/8/11 星期三22What would you do if:Plan of actionYou were offshore but you needed more food and water.Follow nesting birds to shore;look for special cloud formations or fog over streams to fin
26、d land.2021/8/11 星期三23What would you do if:Plan of actionYou wanted to keep a straight course.Use a compass.2021/8/11 星期三24What would you do if:Plan of actionYou were lost with no land in sight.Measure your position using the sun or stars;look for sea birds,cloud formations,fog or seaweed to show th
27、at land is nearby.2021/8/11 星期三254.Read the passage again and 4.Read the passage again and use the information to analyze use the information to analyze the navigational skills.the navigational skills.2021/8/11 星期三26Using nature1.To find the ships position at sea a sailor 1.To find the ships positio
28、n at sea a sailor used used the North Star and the sun.the North Star and the sun.2.A sailor knew that land was nearby if he 2.A sailor knew that land was nearby if he saw _saw _ _._.3.Sailors used 3.Sailors used _ _to increase their speed._to increase their speed.fresh seaweed,nesting birds returni
29、ng fresh seaweed,nesting birds returning home in the evening or foghome in the evening or fog sea currents or tides and sea currents or tides and windswinds2021/8/11 星期三274.There were two methods to find longitude:4.There were two methods to find longitude:1)_ 1)_ 2)_ 2)_ Using instrumentsmeasuring
30、time and speedmeasuring time and speedcompass and complicated mathematical compass and complicated mathematical tablestables2021/8/11 星期三285 Write down the working principles of the 5 Write down the working principles of the following instruments:following instruments:Bearing circle:Bearing circle:A
31、strolabe:Astrolabe:to compare the height to compare the height of the sun now with the of the sun now with the position of the sun at position of the sun at midday.midday.to compare the position to compare the position of the ship in relation to of the ship in relation to some stars or the sun some
32、stars or the sun 2021/8/11 星期三29Quadrant:Quadrant:a more precise form of the astrolabe,a more precise form of the astrolabe,to measure how high stars are above to measure how high stars are above the horizon,and compare that the horizon,and compare that measurement with previous measurement with pre
33、vious measurements(using the ship as one of measurements(using the ship as one of the fixed points to find its position)the fixed points to find its position)2021/8/11 星期三30Sextant:an updated version of the an updated version of the quadrant and so it was more quadrant and so it was more accurate,to
34、 measure the accurate,to measure the angle between two fixed angle between two fixed points outside the ship(using points outside the ship(using two mirrors to find the ships two mirrors to find the ships position).position).2021/8/11 星期三31 5.Imagine you are on a boat with 5.Imagine you are on a boa
35、t with twentynine other people.You have a twentynine other people.You have a small box for your personal things small box for your personal things but it can only hole ten items.What but it can only hole ten items.What would you need for a weeks journey would you need for a weeks journey across the
36、North Sea to England?across the North Sea to England?2021/8/11 星期三32CategoryItemsClothesHygiene BeddingGamessoapblanketcards,chessshirt,trousers2021/8/11 星期三33CategoryItemsShoesToolsMedicinesBooksknife,scissorssea-sick tablets,cold medicinenovels,essay collectionswaterproof boots2021/8/11 星期三34Read
37、the passage(Reading)and decide whether the following statements are true(T)or false(F).1.An early method of calculating longitude was to use a knotted rope tied to a log.2.The astrolabe was the first instrument to measure the suns position.3.The quadrant was more precise and simplified than the astr
38、olabe,but still had its shortcoming.TFT2021/8/11 星期三354.Up till now,the most accurate and reliable navigational instrument is the sextant.5.The astrolabe,quadrant and sextant are different kinds of navigational instruments and they have nothing to do with each other.F F2021/8/11 星期三36Type of writing
39、 and summary of SAILING THE OCEAN.TypeSAILING THE OCEANUsing nature to help:Using navigational instruments to help:expositionFinding longitude,Finding latitude Keeping alongside the coastline,using celestial bodies,using wildlife,using the weather,using the sea2021/8/11 星期三37Homework1.Review this passage.2.Preview Learning about language.2021/8/11 星期三382021/8/11 星期三39