He attended University of Mississippi for three years, before moving back to Holly Springs to teach school.

[1][2] Afterward, he moved to Washington, D.C.[3] In 1885 or 1886, Manning joined the U.S. Geological Survey as a civil engineer and worked two years in Massachusetts.

In 1917, they started performing experiments with helium to reduce its price by large margins and save the military millions of dollars.

He held that role until 1924 when he became a consulting engineer with the Pan-American Petroleum & Transport Company for the Bureau of Mines.

He was interred at Oak Hill Cemetery in Washington, D.C.[1][2] Manning was given an honorary Doctor of Engineering degree by the University of Pittsburgh in 1919.