Thanks Robbie.   I've enclosed two documents -- an Excel spread sheet
implementing your formula, and a text output of same.

Cheers,

George Bogatko
gbogatko@intac.com
http://www.intac.com/~gbogatko

 - - -

Roll buildup effect on A-roll speed, assuming ten 2.5-minute tunes,
evenly divided.  Assume standard A-roll beginning tempo is 60 (6.0 feet
per minute).

  Delta = To*(OD/CD - 1)/(N+1)

  To = Initial Tempo = 60
  OD = Outside diameter = 4.7
  CD = core diameter = 3.63
  N = Number of tunes = 10

Initial Tempo 60
Overall Increm't 77.686
Increment per tune 1.7686

                                      Beats Per Minute
                   +-------------------------------------------------
Punchs per quarter |  15/q          12/q          10/q          8/q
MIDI Equivalent    |  8tick/note    10tick        12tick        15tick
                   |
Tune  Tempo        |
1     60           | 96            120           144           180
2     61.7686      | 98.8298       123.537       148.245       185.306
3     63.5372      | 101.66        127.074       152.489       190.612
4     65.3058      | 104.489       130.612       156.734       195.917
5     67.0744      | 107.319       134.149       160.979       201.223
6     68.843       | 110.149       137.686       165.223       206.529
7     70.6116      | 112.979       141.223       169.468       211.835
8     72.3802      | 115.808       144.76        173.712       217.14
9     74.1488      | 118.638       148.298       177.957       222.446
10    75.9174      | 121.468       151.835       182.202       227.752


 [ The numbers seem good, George.  All values relate to "Tempo", i.e.,
 [ 10 times feet-per-minute, and I corrected the column name
 [ accordingly.  Could you please explain the columns under 'Beats
 [ per Minute'?  What's the formula?  -- Robbie