The brand Thales started in creating a unique geometry for analogue audio tracking. This principle combines in an elegant way the advantages of the tried and tested pivoted tonearm with the absolutely tangential tracking. This construction for which a patent was taken out on the 8th of May 2004 reduces the perfectly tangential tracking to pivot points, while the pick-up cartridge is taken and aligned on the Thales' Circle.
Animation (Java needed)
Move point C in the animation above over the record area in order to see the tangential tracking on the Thales' Circle. All triangles ABC on the Thales' Circle around M are rectangular in point C. Thus BC stands rectangular to AC and therefore tangential to the groove (red) with the radius AC. Because the pick-up cartridge is mounted exactly under point C and in the alignment of the straight line BC the tracking is perfectly tangential in every position.