Take one of the standard publisher’s drop cap S images, add a bit of doodle-like accents and you have this large fancy letter S image. I think it looks even better when you shrink it a bit! This image was included in the interesting book about Triumphs of Invention and Discovery in Art and Science which was published by T. Nelson and Sons of London in 1871.
This image is copyright free and in the public domain anywhere that extends copyrights 70 years after death or at least 120 years after publication when the original illustrator is unknown.