Stillman Taylor, Popular Mechanics, November 1915
https://books.google.com/books?id=td8DAAAAMBAJ&pg=PA784&lpg

Obviously not a Vic Venters quality study, but interesting.

Can anyone ID the maker? A 2 piece mainspring with a roller-bearing.

[Linked Image from photos.smugmug.com]

Tobin used a roller-bearing on the short arm of the mainspring

[Linked Image from photos.smugmug.com]

[Linked Image from photos.smugmug.com]

An illustration of what appears to be the Alexander Brown "Double Cross Bolted Treble Wedge Rib Extension", with an odd non-Smith lump. Did another U.S. maker use the rotary bolt?

[Linked Image from photos.smugmug.com]

[Linked Image from photos.smugmug.com]