HelenAnn - only because I've looked at so, so many of these. So I know that particular design is not an early machine - the fatter head, tension on the face (not leaf) are a few things. Mostly it's because I've spent a ton of time on Needlebar paying attention to differences so I'd know what I was looking for. One of the hard parts with this - National used most of the same names that Eldredge had used prior to the merge, especially the name Eldredge.
The short story - going from memory here - Eldredge came up with an idea, found a company to make his machines - then moved west and joined up with June to make the machines (June made their own too) and after the guy owning June died, Eldredge merged the two companies and formed National.