A brief history of the compass and the compass rose
A form of compass that points South has been known in China since around 200 B.C. The Chinese originally employed this technology for fortune telling, and to help in aligning houses with the cardinal points of the compass for religious and good luck superstitions. It wasn’t until the late 13th Century A.D. that a Chinese ship is known to have navigated with a Compass. In Europe the first Historically recorded mention of a compass used for navigation dates to 1190 A.D. This fact coupled with the fact that European compasses have always pointed North rather than South has caused many to speculate that Europeans invented the Compass independently in the 12th Century A.D. The classic story is, however, that it arrived in Europe via the famous Silk Road, but to do that it would have had to come through the Middle East, and Middle Eastern mentions of the compass date to a time after the European mention, and the Arabic word for compass seems to have Italian rather than Chinese origins. Furthermore, its advent comes at a time when trade on the silk road is in decline due to barbarian incursions.
All that is, of course, beside the point. The point is that the compass became a very useful aid to sea navigation, and thus transportation in the 12th and 13th Centuries A.D. This navigational aid increased trade between the Mediterranean and Northern Europe, and increased the confidence of navigators against being lost at sea to the point that the Great Age of Exploration would soon ensue.
The compass is actually a simple magnetic device that indicates direction due to the natural tendency of magnetic materials to align their poles with the poles of the Earth’s own magnetic field. A Navigator using a compass can determine the cardinal directions of north, south, east, and west with very little error from almost anywhere in the world. There is error in compasses from sources such as being too close to the earth’s poles, natural iron ore deposits, natural electric charges and fields, even a wooden ship has a magnetic field when on the water, but in most ordinary circumstances these errors are too slight to cause significant confusion to a navigator.
Maps and compasses can be used together by orienting the map. To do this the compass rose came to be included on the map. It is merely a diagram pointing to the various divisions of the cardinal directions. In early navigation rather than calling them north northwest, or south southwest, or whatever they named the directions for the winds already known to sailors (i.e. levant, sirocco, greco, etc.). It is very posible that the compass rose actually predates the compass, and that the maps were originally oriented by known prevailing winds. The compass rose appears to have gotten its name due to the elaborate decorative style of early cartographers making it look much like a flower in the corner of the map. Compass roses range from simple criss-crossing arrows, to beautiful multicolor works of art.
By the time Christopher Columbus crossed the Atlantic with two caravels and a carrack, navigators were old hands at using the compass to orient themselves. Early compasses were a lodestone (natural earth magnet) attached to a disc floating in liquid or balanced on a central pin. But it was discovered that iron left a long time in contact with a magnet would act as a magnet itself. Thus magnetized needles replaced discs, and eventually led to the pocket compass.
Add a sextant to a compass, and you can pinpoint your latitude on any map if you can see the sun or a known star for which you have charts or tables. Longitude took a little longer to master, and was first accurately and repeatedly pratically applied by Captain James Cook. Cook figured longitude first by measuring the angle of the moon, and later using a chronometer set to the time at Greenwich England which would become the predominate method in years to come.
