Steven Harriman Long 

http://www.topogs.org/b_long.html

http://www.dlwgraphics.com/mnlng2.htm

Joseph Swift to Alden Partridge, 1815 March 15, informs that Long is to be an assistant to Ellicott. Partridge papers, USMA, Box2.

What is to be made of his middle name?

Bibliography:

Nichols, Roger L. and Patrick L. Halley. Stephen Long and American Frontier Exploration. Newark : University of Delaware Press, c1980. USMA:    F592 .N48 

Wood, Richard George, Stephen Harriman Long, 1784-1864: army engineer, explorer, inventor, 
Glendale, Calif., A.H. Clark Co., l966. USMA:    UG128.L6 W85s