Final answer:
The system of navigation aids in the Western Rivers System, such as the Mississippi River, includes the use of natural landmarks and careful observations of latitude and longitude to navigate. Variations of the compass in different locations also need to be considered. These practices were developed to accommodate the unique characteristics of the river and its tributaries.
Step-by-step explanation:
The system of navigation aids on the Mississippi River and its tributaries above Louisiana, known as the Western Rivers System, has some differences compared to the system of navigation aids in the rest of the United States. One key difference is the presence of specific markers and objects used for navigation.
In the Western Rivers System, there is a focus on using natural landmarks, such as river mouths, rapids, islands, and other durable features, as reference points for navigation. This information was gathered through careful observations of latitude and longitude at these points. The compass, log-line, and time were used to fill in the courses between these observation points.
Another difference is the need to consider the variations of the compass in different places along the river. This is important because the magnetic compass needle can point slightly differently in various locations due to the Earth's magnetic field. Captains and navigators on Western Rivers had to note these variations to ensure accurate navigation.
These different navigation practices in the Western Rivers System were developed based on the unique characteristics of the Mississippi River and its tributaries. The ever-changing nature of the river's path and the extensive network of interconnected waterways required a specific system of navigation aids to ensure safe and efficient boating.