* Dead reckoning: This is a method of navigation that involves estimating the distance traveled based on the direction and speed of travel. Lewis and Clark used a compass to determine their direction, and they estimated their speed by counting the number of steps they took or by using a stopwatch.
* Landmark method In this method, they used prominent natural features such as rivers, mountains, or distinctive landmarks as reference points to estimate the distance traveled. By noting the distance between these landmarks and comparing it with the known distances between them, Lewis and Clark could make rough estimates of the distances covered.
* Celestial navigation: This is a method of navigation that involves using the position of the stars to determine one's location. Lewis and Clark used a sextant to measure the angle between the horizon and a star, and then used trigonometry to calculate their latitude. They also used a chronometer to measure the time of day, which allowed them to calculate their longitude.
* Log Line and Lead line They also used a log line, a rope with knots tied at measured intervals, to estimate the ship's speed through the water. By throwing the log line overboard and timing how long it took for the knots to pass a fixed point on the ship's deck, they could calculate the speed. Similarly, they used a lead line to measure the depth of the water, which helped them navigate safely in shallow areas and avoid obstacles.
By using these methods, Lewis and Clark were able to calculate the distance that they traveled with a high degree of accuracy. This was important, as it allowed them to map their route and to estimate their progress.