STANDARDS OF LINEAR MEASURE. 
369 
Wishing to ascertain whether the curvatures of both halves of the scale were 
similar, I took the distance from 24 to 60 inches. 
With wires .04 of an inch diameter. 
From 24 to 60 inches. 
Without Wires. 
A Wire under 
Wires under 
Error when curved 
Error when curved 
Sum of 
the middle. 
the ends. 
upwards. 
downwards. 
Errors. 
div. 
div. 
div. 
div. 
div. 
div. 
41.0 
24.0 
44.0 
38,0 
21.0 
44.0 
126.0 
104.0 
129.0 
Mean 68.3 
49-7 
72.3 
19-4 
3.2 
22.6 
0.8 Reduction to the Chord. 
69.1 
Here we perceive that the sum of the errors is very nearly the same as be- 
fore ; but there is an irregularity in the curvature, or rather a difference in the 
place of the neutral plane of the two halves of the bar, which deserves parti- 
cular attention ; for instead of the error being less, as in all the preceding ex- 
periments, when a wire is placed under the middle, than it is when the extre r 
mities of the bar are supported, it is here greater. We may also remark that 
the difference between the means of the readings “ without wires” is 27*7 
divisions, which shows that the distance from 24 to 60 inches of the scale is 
shorter than that from 0 to 36 inches .001187 of an inch. 
With wires .05 of an inch diameter. 
From 0 to 36 inches. 
(H.) 
Without Wires. 
A Wire under 
the middle. 
Wires under 
the ends. 
Error when curved 
upwards. 
Error when curved 
downwards. 
Sum of 
Errors. 
div. 
div. 
div. 
div. 
div. 
div. 
14.5 
7.5 
39.5 
13.0 
3.5 
33.0 
11.5 
4.0 
31.2 
8.5 
4.0 
36.7 
7.0 
0.0 
32.0 
Mean 10-9 
3.8 
34.5 
8.3 
22.4 
30.7 
1.2 Reduction to the i 
2hord. 
12.1 
3 b 2 
