According to a timeline located in Mr. Lovelace's book, that date is the day Governor Locke Craig christened the railroad.
The book citation can be found in the references for the article. It is: Lovelace, Jeff. 1994. Mount Mitchell: its railroad and toll road. Johnson City, Tenn: Overmountain Press
I hope this helps, if you have any more questions please feel free to post here again.
Christopher Luettger - NC Government and Heritage Library