(5 ) 
as compared to the first is that the influence of the temperature has 
been more variable. 
This however is mainly the case only for the last years, when, evi- 
dently, the cleaning of the clock had been already too long deferred. 
If we reduce the temperature-coefficient found for the third period 
to what it becomes for 1° R. instead of for 1° C., if further we reduce the 
mean coefficient of the first period to the value which would have 
been found, had not the barometer-reading been reduced to 0°, and 
if, lastly, we add the value found for the middle part of the second 
period '), leaving the quadratic terms out of consideration throughout, 
we find: 
1862—1874 c = — 0:.0196 
1885—1891 — 0.0269 
1899—1902 — 0.0275 
Between the 2nd and the 34 period the pendulum has not been 
taken to pieces and only a small stain of rust has been removed 
from the suspension-spring. 
25. Let us now consider the results obtained for the supplemen- 
tary inequality. Setting aside a half-yearly inequality, sometimes 
shown, which is connected with the precise form of the influence 
of the temperature, we find in all the periods a supplementary yearly 
inequality in the rates which can be nearly represented by a simple 
sinusoid having its maxima about May 1 and November I, the semi- 
amplitude of which amounts to: 
1862—1874 + 0:.0341 
1878—1886 0455 
1887—1896 ‚0254 
1899—1902 0465 
In the latter part of the period 1878—1898 the amplitude of the 
supplementary inequality seems to have appreciably diminished so 
that in the years 1897—1898 it is hardly sensible. For the rest 
the amplitude of the inequality appears to have had nearly the same 
amount under any circumstances. 
The question now arises: 
What explanation can be offered of this inequality ? If we consider 
only the monthly rates, we may mathematically represent it as a 
lagging behind of about half a month of the influence of the tem- 
perature. This cannot be the true physical explanation, however, 
1) See also the va'ues of ¢ for the 2nd period on p. 20 (87). 
