John Blenkinsop
The first practical railway locomotive was built by John Blenkinsop in 1811, well before the opening of the first proper railway, namely the Liverpool and Manchester Railway in 1830. It was a cog locomotive because Blenkinsop didn't believe the mere friction would work even on level track. The LMR was laid out with gentle gradients on the flatter sections of 1 in 1000 or 1 in 2000, with 1 in 100 gradients concentrated on either side of the Rainhill Level, just in case rope haulage proved necessary. In the event, Stephenson's Rocket could indeed manage 1 in 100 grades.