Transcript Compass
Work done by : Yitong Wang Sophia Yiu Gaohong Liu Hanlun Zhou [email protected] [email protected] [email protected] [email protected] Project 1 Physics 001 Section 001 Before the Invention of Compass--The Area of navigation is dark and cloudy! People can’t go far without compass and nearly know nothing about the world outside. Before compass’s invention, people use cordierite to determine the sun's direction and some lagging methods to determine four basic directions. Introduction Compass is used to determine position of a simple instrument. Formerly known as Sinan. The main components are mounted on a shaft can freely rotate the needle (commonly known as magnet). Needle on the ground magnetic field can be maintained at the tangent magnetic radial direction. Needle points to the geographical North Pole South Pole, take advantage of this performance can be a sense of direction. Commonly used in navigation, geodesy, travel and military and so on. The magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since about 206 BC), Formerly known as Sinan. The compass was used in Song Dynasty China by the military for navigational orienteering by 1040-1044, and was used for maritime navigation by 1111 to 1117. The use of a compass is recorded in Western Europe between 1187 and 1202, and in Persia in 1232. The dry compass was invented in Europe around 1300. This was supplanted in the early 20th century by the liquid-filled magnetic compass. (Wikipedia http://en.wikipedia.org/wiki/Compass#Using_a_compass) Compass invented the ancient Chinese practice of long-term understanding of the results of magnetic objects. Ancient Chinese people into contact with magnetite, as he began to understand the nature of magnetism. It cited the first to discover the magnetic properties of iron. Then they discovered that the directivity of the magnet. After many experiments and studies, and finally invented the compass can be useful. The Earth is also a big magnet, and its two very near the geographic South Pole, respectively, and the geographical North Pole areas. Therefore, the Earth's surface magnets, free to rotate, they will repel the same sex due to magnet, opposites attract nature of the north-south direction. This principle is not enough to understand the ancients, but such phenomena they are very clear. The working Principle of SINAN A working model of the oldest instrument in the world which is known to be a compass. The spoon or ladle is of magnetic lodestone, and the plate is of Bronze. The circular center represents Heaven, and the square plate represents Earth . The handle of the spoon points south. The spoon is a symbolic representation of the Great Bear. The plate bears Chinese characters which denote the eight main directions of north, north-east, east, etc., and symbols from the I Ching oracle books which were correlated with directions. Separately marked are the finer gradations of twenty-four compass points, and along the outermost edge are the twenty-eight lunar mansions. This type of compass has been scientifically tested and found to work tolerably well - It was used not for navigation, but for quasi- magical purposes.(ORACLE Think Quest http://library.thinkquest.org/23062/compass.html) The Working Principle of magnetic compass In ancient times, the sailors who used a magnetic compass to navigate, believed that a group of stars or a mysterious range of iron capped mountains in the north regulate its working. In China, the magnetized iron found in the lodestone, a naturally occurring magnetic ore was used to make a floating compass in the 12th century. A piece of magnetized iron placed on a wooden splinter and floated in a bowl of water would itself swing to north-south direction. A small pocket compass works on the same principle as the first crude compass: instead of a lodestone and a wood splinter, it has magnetized needle that swings on a pivot to indicate north. The compass works because earth itself is a huge magnet. Its magnetic poles are oval areas about 2100 Km from the geographic north and south poles. The magnetic North Pole is in Canada and the magnetic South Pole is near Antarctica. Irregular lines of force connect the magnetic poles and the compass needle simply aligns itself with these lines of force. (http://www.abhigyan.com/TreasurePage/MagneticCompass.htm) The Significant Impact of Compass The invention of Compass certainly has some significant impacts on human’s world and society. We concluded that there are basically four biggest impacts of compass. 1. Supporting Navigation, helping people discover the new continent 2. Used as building orientation 3. Supporting Mining 4. Supporting Astronomy Impact on Navigation Prior to the introduction of the compass, position, destination, and direction at sea were primarily determined by the sighting of landmarks, supplemented with the observation of the position of celestial bodies. On cloudy days, the Vikings may have used cordierite to determine the sun's direction and elevation from the polarization of daylight; their astronomical knowledge was sufficient to let them use this information to determine their proper heading. For more southerly Europeans unacquainted with this technique, the invention of the compass enabled the determination of heading when the sky was overcast or foggy. This enabled mariners to navigate safely far from land, increasing sea trade, and contributing to the Age of Discovery.(http://en.wikipedia.org/wiki/Compass#Using_a_compass) As Building Orientation Evidence for the orientation of buildings by the means of a magnetic compass can be found in 12th century Denmark: one fourth of its 570 Romanesque churches are rotated by 5-15 degrees clockwise from true east-west, thus corresponding to the predominant magnetic declination of the time of their construction. Most of these churches were built in the 12th century, indicating a fairly common usage of magnetic compasses in Europe by then. (http://en.wikipedia.org/wiki/Compass#Using_a_compass) Impact on Mining The use of a compass as a direction finder underground was pioneered by the Tuscan mining town Massa where floating magnetic needles were employed for determining tunneling and defining the claims of the various mining companies as early as the 13th century. In the second half of the 15th century, the compass became standard equipment for Tyrolian miners. (http://en.wikipedia.org/wiki/Compass#Using_a_compass) Impact on Astronomy In the 14th century, the Syrian astronomer and timekeeper Ibn al-Shatir (1304–1375) invented a timekeeping device incorporating both a universal sundial and a magnetic compass. He invented it for the purpose of finding the times of salat prayers. Arab navigators also introduced the 32-point compass rose during this time. (http://en.wikipedia.org/wiki/Compass#Using_a_compass) Reference and Citations Knowing Your Way – Compass ORACLE Think Quest http://library.thinkquest.org/23062/compass.html Working Principle of a compass http://www.abhigyan.com/TreasurePage/MagneticComp ass.htm Compass Wikipedia http://en.wikipedia.org/wiki/Compass#Using_a_compass A short and interesting video introducing compass Magnetic Compass Purple History Thank you!