( 223 ) 
PAB BIV, 
Bosihion Capacity Capacity 
of the Diff. 
glass plate observed. calculated. 
| | 
PD ae 5° 2.920 — — 
4.080 
52n25 7.000 6.988 0.012 
4,220 
80.10 11.220 15235 0.013 
4,445 
103.70 15.661 15.663 0.002 
with one adjustable condenser were repeated ceteris paribus. 
Each of the numbers given in the above four tables is deduced from 
three readings, two with the condenser Nj and one with Ns. The 
values which are given in the second column of Tables II, III 
and IV have a larger inaccuracy, since the errors of direct reading 
are added to the eventually similar errors of the calibration curve. 
But all the values are the mean of four series of three observations, 
so the required error is reduced to 0.12 mm. This is in accordance 
with the maximum error seen in the Tables II to IV which is 
0.13 mm., while most are much smaller. 
These considerations are not however very precise, for the calcula- 
tion of a capacity from the calibration curve implies the use of 
more than one observation, and the values „Capacity calculated” are 
derived from all the observations. Hence the calculated error must 
be greater than 0.12 mm., and therefore the maximum error of 
0.019 in the capacity — or of 0.13 mm. in the position of the glass 
plate — is entirely explicable from the reading errors. This result 
leaves no doubt as to the accuracy of the principle of the expe- 
riments. 
5. Measurements. 
The final determinations were made in the following manner. 
The adjustable condenser MN, was set at 21.45 and the key T (Fig. 
3) opened, equilibrium was then attained by connecting up the 
auxiliary capacity and adjusting Ns. The key 7 was then closed 
and 4, readjusted until equilibrium was again established. If now 
we call z, and zj the capacities of MN; in the first and second positions 
respectively, y the capacity of the electrometer and its leads including 
the wire from H to the key 7, d that of the wire from T to the 
: 16 
Proceedings Royal Acad, Amsterdam, Vol. IL. 
