Born in Brooklyn, New York in 1855 - Frederick Newton Willson was an eminent authority (a true OG) of Geometry and Mechanical Drawing throughout the 20th century.
He was a revered (awesome) teacher at the prestigious (expensive) Princeton University in New Jersey, USA where he taught Geometry. Under his inspiring guidance 'a long succession of students produced a wealth of excellent drawings'. 
During this time, he published a series of books on his expert subject matter, none more famous than Mechanical Graphics - An educational course on the theory and practice of mechanical drawing - published in 1890.
We purchased a copy of this book and studied it closely. Throughout the book are examples of technical drawings of various random objects. Then as the book goes on, we come across some of the earliest examples of 'block' lettering designs, purposely created to be replicated and used over and over again.
It is within page 12 that we have a selection of letters and short words, to demonstrate technical drawings of certain 'block' letters. It is smack bang in the middle of this drawing that we see a very early version of 'The S'.
Some claim a very close similarity whilst others claim the S is too rounded or flat.
Whilst you can argue that there are certainly 6 lines to start off this particular S, we're not so convinced this specific design is closer than others we have discovered at different stages of the timeline.
What is more apparent to this story, is Frederick Willson was a pioneer of graphical lettering and his expert influence was a driving force during the early 1900's. One can certainly dream up a scenario where the professor dedicated times in his lesson to teach his students how to draw 'the S' (his S) and perhaps that started off a ripple effect that tapped into the addictive nature of drawing it. But to say it was THE origin of 'The S' is a big stretch. Sorry LEMMiNO.