In the nineteenth century what was the most invention or inventor and why.

One could argue that the cotton gin, invented by Eli Whitney, was the most helpful invention of the 19th century.The cotton gin revolutionized the cotton picking industry because it made the work faster; instead of slaves having to pick the cotton seeds out by hands, this machine could pick out the seeds in less than half the time. This caused an increase in cotton production because since pure cotton could be turned out faster so came the demand to have more cotton to de-seed.