The field of tape-recorders is ripe for some form of standardization. Except that speeds are supposed to be standardized (though a tape recorded on one model of a well-known make plays a semitone sharp on a newer model of the same make) most other things seem to be totally variable. This particular article was inspired by the frustration arising from the fact that some counters count the turns of the run-off spool, while others count the turns of the take-up spool. (Some counters only count every other turn; we shall ignore this wholly unnecessary complication.) The question is: how does one convert a reading from one type of counter to that from the other? This produces an unexpected graph in the form of a circular arc—a rarity which perhaps justifies a note.