That's interesting. It looks like an early form of resonator guitar, using banjo technology, and it fits in well with the many pre-electric attempts to make a louder guitar, the most renowned attempt being the Dopyera brothers' "Dobro" in the early 1920s.

Ignoring Dave Oesterreich's intervention (is it possible to have a thread on here without denigrating someone else's preferred genre of music?) It is possible that Mr Flemming would have been intending his invention to be played in slide style, but at that time the slide influence would have been from African sources. There are many suggestions of African derived folk instruments being played with knife handles and such.
Hawaiian slide, according to legend, originates with Joseph Kekuku about ten years later, in the mid 1890s, when he slid a railway spike along the strings of a guitar donated by Portugese cattle men.
It would be a big contribution to understanding the origins of slide guitar in Blues if evidence could be found as to how Flemming's guitar was played, assuming that the evidence pointed in that direction.
Sadly, it does not seem to do so. The Nut is shown as low, which inplies finger fretting.
Cheers
Dave