The planes or vectors of grooves (especially of some pre 1920s acoustic
'78s') need not be horizontal (lateral) nor vertical (hill 'n' dale). They
can be diagonal. Such disks were claimed to be 'compatible' & ostensibly
suited for lateral and vertical 'talking machines'. Typical mechanical
compliances of the pickups rendered such disks meaningfully less than
optimal on lateral & vertical machines.
It's my opinion that it wasn't until a modern ('post Blumlein') stereo
cartridge was made and fitted with an appropriate stylus that such disks
could be played 'optimally' (meaning, as well as such disks could
theoretically be tracked). The technically best 'compatible' ones that I've
encountered were made by Arto.
BTW is it known if Victor ever attempted or took action against Arto for its
knockoff of Victor's 'batwing' label design?
I'm not using 'phonographs' because due to copyrights ,some manufacturers
used different terms. i.e. Columbia did not make disk phonographs. It made
Grafonolas and Graphophones.
Art (Shiffy) Shifrin