80 turns 38.144
90 turns 38.142
100 turns 38.140
110 turns 38.138
120 turns 38.135
130 turns 38.132
140 turns 38.130

On comparing the scale with the standard meter, the temperature being
16°.5 C., 140 divisions were found to = 139.462mm. This multiplied by
(1 + .0000188 × 16.5) = 139.505mm.

One hundred and forty divisions were found to be equal to 140.022 turns
of the screw, whence 140 turns of the screw = 139.483mm, or
1 turn of the screw = 0.996305mm.

This is the _average_ value of one turn in 140.

But the average value of D, for 140 turns is, from the preceding table,
38.130.

Therefore, the true value of D, is 38.130 × .996305mm, and the average
value of one turn for 10, 20, 30, etc., turns, is found by dividing
38.130 × .996305 by the values of D;, given in the table.

This gives the value of a turn--

mm.
For the first 10 turns 0.99570
20 turns 0.99570