What I did:
I just borrowed two issues of National Geography. Due to my weakness in reading, I decided to read several articles on it and summarised them. Hence, I wrote down what I had learned.
What I learned:
From the National Geography, I learned about the imaginations drown by cartographers. In the ancient time, the urgent needs of maps caused the appearance of the job cartographers. However, due to the lack in the sailing vehicle and the technology on sailing, cartographers could not draw the entire ocean in a single map because they did not know what was beyond their discovered world. Besides, the disasters like large waves terrified the voyagers and the cartographers. In addition, It was a common idea that the more horrible the monsters on the map were, the more the map could be sold. Hence, due to the Geographic factor and the Economic factor, there were a lot of monsters like sirens and sea dragons on the ancient maps.