Complex sentence: Gatling was born in Hertford County, North Carolina, in 1818 at the age of 21, Gatling created a screw propeller for steamboats, without realizing that one had been patented just months prior by John Ericsson.
Split into simpler sentences: Gatling was born in Hertford County, North Carolina, in 1818. At the age of 21, Gatling created a screw propeller for steamboats, without realizing that one had been patented just months prior by John Ericsson.