Sunday, April 7, 1805 was a “double departure day” in the timeline of the Corps of Discovery. Captains Lewis and Clark prepared to depart Fort Mandan and to send back plant and animal collections, including a live prairie dog.
When we think of the Lewis and Clark journals, we imagine the writers working with quill pens and a small-batch of ink mixed from a dry powder. There’s no mention of pencils in the supply list of Meriwether Lewis.
Lewis and Clark used several instruments and lots of math to calculate their latitude, longitude and altitude as they traversed across the Great Plains and Rocky Mountains. But did you know, in the Northern Hemisphere you can accomplish some of these same calculations using only your hands? Test out some of these tricks; maybe they’ll come in handy on your next adventure!
Aaron Arrowsmith was considered the finest mapmaker of his day -- a surveyor who quickly established himself as a mapmaker and publisher with an international reputation.
One of Arrowsmith’s 1802 map editions would be carried by Lewis and Clark, since it was the most comprehensive map of the West available at that time.
Watches and clocks are so common today we take them for granted. They’re on our wrists, our kitchen microwaves, our computers, our cars, and our phones. But in the early 19th century, clocks, or chronometers as they were known then, were rare and expensive instruments.
As they set off on their epic journey of many purposes, Captains Lewis and Clark took along a wide array of mathematical instruments to help them chart and survey the nation’s land acquisition. This set of sophisticated tools included a theodolite – used to measure vertical and horizontal angles.
When Meriwether Lewis and William Clark set out towards the Pacific Ocean in 1803, they carried a supply of mathematical instruments and tools for navigation. In addition to helping them chart a course, these instruments enabled them to document the newly-acquired landscape of the young United States. Their efforts also continue to be important today for understanding the land, its inhabitants, and the cartographic skill of Captain William Clark.
Believing they were close to the mouth of the Yellowstone, Captain Lewis took a few men and some of his instruments and walked to the confluence in order to take navigational observations. He wrote in his journals, “I could not discover the junction of the rivers immediately, they being concealed by the woods, however, sensible that it could not be distant I determined to encamp on the bank of the Yellow stone river which made it's appearance about 2 miles South of me.”
