For the _first_
10 turns the _average_ value of D′ is 38.155
20 turns 38.153
30 turns 38.152
40 turns 38.151
50 turns 38.149
60 turns 38.148
70 turns 38.146
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.