This is one example of many castles in the medieval time period. There were many parts to a castle. But, it depended on how the castle was built to recognize parts that did and did not appear on the castle built.
Like spray paint, these markers give off volatile organic compounds. Some of the most recently made permanent markers are made from recycled plastic.[citation needed] The permanent marker was invented in 1952 by Sidney Rosenthal.
The earliest compasses were made of lodestones. This mineral is made of iron oxide which orients itself to a north and south axis.In 1117 Zhu Yu's book Pingzhou Table Talks came out.It was the first time in the history of the compass that the device was mentioned as a tool for navigation.Later in the 8th Century A.D, magnetic needles replaced the loadstones. From the 8th century to 1050's, compass were actively used in ships. The compass was first invented in the Han dynasty, but further improvements were made in the Song dynasty.