370 
CAPTAIN KATER ON THE ERROR IN 
With wires 0.5 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. 
41.5 
23.0 
48.0 
39.5 
18.5 
50.0 
39.5 
19-0 
49-0 
38.7 
15.7 
48.5 
35.0 
16.0 
45.0 
Mean 38.8 
18.4 
48.1 
21.6 
8.1 
29-7 
1.2 Reduction to the Chord. 
40.0 
From this Table the same conclusions may be drawn as from Table (G), as 
to the place of the neutral plane in the two halves of the bar. I am disposed 
to attribute this irregularity to the manner in which the scale is constructed, as 
it consists of a bar of cast brass, to which is soldered a piece of plate brass, 
upon which the divisions are traced. The difference between the distance 
from 24 to 60 inches and from 0 to 36 inches does not differ sensibly from that 
before found, namely .001187 of an inch. I should have observed that the 
comparisons of the distance from 0 to 36 and from 24 to 60 inches on the 
scale immediately followed each other, that is, the microscopes were trans- 
ferred immediately from one part of the scale to the other. ' 
Wishing to try the effect of an increased curvature, the following compa- 
risons were made. 
With wires 0.1 of an inch diameter. 
From 12 to 48 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. 
81.0 
51.5 
121.0 
83.5 
51.0 
117-0 
86.0 
53.0 
120.0 
83.0 
51.0 
120.0 
Mean 83.4 
51.6 
119.5 
36.8 
31.1 
67-9 
5.0 Reduction to the Chord. 
88.4 
