Thank you Colin. Perhaps I was not as precise as I could have been. If I tune an interval at A440 from C to G for argument's sake in temperament "T", the rate of beat will be N. Agreed, if I then tune C to G at A415 in the same temperament, the rate of beat will remain N. However when I listen to the interval C to G perceived at A440 but tuned at A415, ie C#/G#, the rate of beat and hence the aural perception of that interval will be different. My point being that our ears have become so accustomed to hearing sounds at or about A440 that our perception of "out of tuneness" will be very different to that of Wesley's.