Pam Turner, inventor of the Spiral Eye side threading needle.
The "other" easy to thread needle...
The Calyx eye (AKA "French Spring eye" or "self threading needle") was invented in 1850. It has the opening located at the end of the eye portion of the needle.
This crack in the top of the needle was intended to allow you to thread it, but not let the thread out. Unfortunately this is not what happens. Most users complain that they come un-threaded easily when they sew and often times they shred their thread when inserting them.
Photo is of a Calyx Eye needle next to a side threading needl