constructed which gave the following values for this distance, which we
shall call D′:

Turns of screw.
At 0 of scale D′ =38.155
10 of scale D′ 38.155
20 of scale D′ 38.150
30 of scale D′ 38 150
40 of scale D′ 38.145
50 of scale D′ 38.140
60 of scale D′ 38.140
70 of scale D′ 38.130
80 of scale D′ 38.130
90 of scale D′ 38.125
100 of scale D′ 38.120
110 of scale D′ 38.110
120 of scale D′ 38.105
130 of scale D′ 38.100
140 of scale D′ 38.100

Changing the form of this table, we find that,--

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