It is pretty clear, aurally, whether a player is playing with the guitar held upright, or as you say "bottleneck" style, or lap style, which, by the way, does not necessarily imply the use of a hard edged knife. Many such as Mance Lipscombe, played upright with the back of the knife, which was often rounded, not square. Some would use the bone of the handle, etc. And some would use round edged steels made specifically for the purpose, then as they are today. I have an Oahu steel that was probably made in the '30s.
If a player fretted notes, while also using a slide, as, for instance, Robert Johnson did, they were playing upright, and likely using a bottleneck or pipe which would stay on the pinky finger while fretting with the other fingers. Fretting while playing lap style, in which the strings are usually raised, is cumbersome at best and generally impossible. Patton never fretted while playing slide, and most who listen closely before making pronouncements feel he likely did play lap style.
Yes, fretting well above the neck join is another good clue, but not an impossibility while playing upright/bottleneck. I have seen several accomplished players flip their left hand palm up to slide well beyond the neck join while playing upright.
Listen for fretted notes. If you hear them, the player is holding the guitar upright. If you only hear slide or open notes, there is a good possibility, though not a certainty, the player is using lap style. Both of these styles were commonly used in the pre war era.
Also, these players were intelligent enough to know that if they wanted to tune excessively high they should put lighter strings on their guitar. Most pre war players used a much lighter (.018') plain 3rd string, which would reduce tension somewhat as well. Try this, move all the strings of a light set over one string, and leave off the bass string. Then sub in a .009" or even just another .012 for the high E string. Now tune up to Standard at F# or G (I don't believe Patton went above F# in Standard, or B in Spanish). Feels about right, doesn't it, and you end up with a plain .016" third string. I tune my 95 year old, well bellied Stella, strung with lights and a plain .018" third, up to Spanish at A and leave it there til next session without a care. Been doing that for 15 years and notice no change in action over that time. These guitars are built light, but not poorly, and they play best when played hard.
There's no indication that Patton was playing and not just posing in that picture. He most likely would have had the guitar flat on his lap if he was actually playing. The photographer probably asked him to hold it up so the guitar was more visible.
Your cat has no claws and the pigeons are chortling. There is endless aural evidence, but you likely have your evidence from books. Listen, experience, experiment, see what you find out.
: Just to put a cat among the pigeons, I was
: wondering if there's any actual evidence
: that Patton, Blind Willie Johnson, Robert
: Johnson, or anyone one else, for that
: matter, actually played and/or recorded
: using what we now call
: "bottleneck" style guitar in the
: 1920s or '30s?
: Enlargements of the (relatively) recently
: discovered "studio" portrait of
: Patton, clearly shows him playing
: "knife" style on a "12
: fret" parlour held at 45 degrees on his
: Further evidence in favour of Patton's use
: of "knife" style, comes from
: recordings like "When Your Way Gets
: Dark", played in open A, which features
: regular slide excursions up to the 17th fret
: (assuming he was tuned 'up' to open A, or
: the 19th fret, if he was tuned 'down' to
: open G and capoed at the 2nd fret), which
: are hardly easy to play
: "bottleneck" style. This lick
: found it's way into Robert Johnson's
: "Come On In My Kitchen".
: Both Patton and Johnson also often tended to
: play slide out of 'Spanish' tuning pitched
: in keys as high as B and B flat.
: We tend to forget that pre-war steel string
: sets came in just one gauge: 14 to 64. Prior
: to the mid-'30s, guitars had no adjustable
: truss rods and only a few, top-of-the-line,
: instruments even had an inert truss rod.
: Cheaper instruments within the financial
: reach of blues players would not have been
: able to take the string tension of a set of
: steel strings tuned to open A without
: Just in standard tuning, a string set like
: this tuned to concert on a guitar with a
: 24.8" scale, generates 220 lb ft of
: torque on a guitar bridge. That's probably
: more than the peak torque your car puts down
: to the road through its driven wheels.
: Skip James recorded using a Stella 12
: string, strung with only 6 strings and tuned
: down to "cross note" 3 frets below
: I suspect everyone else tuned down and used
: a capo. Try playing bottleneck on a "12
: fret", tuned to open G and capoed at
: the 4th fret to play in the key of B. What
: used to be your 12th fret is now fret 16.
: Now play that Patton lick that used to go to
: fret 17, but which now goes from fret 16 to
: fret 21. Easy, isn't it?
: Now forget about "bottleneck" and
: play it "knife" style, as I'm
: convinced they did, back in the day.
: Any thoughts?