I researched it for hours last night and found the patent and the secret to what makes it tick so to speak.
It is a very interesting design, I have seen knives with covered back springs before but this one is more than that. It also has a unique bolster and handle fastening system.
The knife was designed by William Schmachtenberg of New York City, the patent was applied for on Dec. 11, 1890 and patent received on March 31, 1891.
Here is a link to the patent: https://www.google.com/patents/US449499 ... CDUQ6AEwAA
The primary reason for the invention was this:
Like almost all these inventions they ultimately proved to be unprofitable to make and the conventional design folding knife lasted the longest while these were a "flash in the pan".This invention relates to improvements in the manufacture of pocket-knives, and has for its objects to produce a cheap, neat, well finished knife by a plan of construction that will expedite the work and render the finished product substantial.
Luckily there are still some left around today to study and marvel over.