(72 ) 
definitive discussion of the time-determinations during that period. For 
the following years they were taken from the provisional results which 
had been computed immediately after the observations, Mr. Wrrprr’s 
results being not yet completed last year. L only applied small corrections 
in a few cases for the personal differences between the observers, 
which have become better known since the provisional computations 
were made. I always used time-determinations as near as possible to 
the beginning of each month. 
The mean temperatures and barometerreadings required for the inves- 
tigation were derived in the following way. 
The temperature was read on two thermometers suspended in 
the clock-case, one at the level of the upper part of the pendulum rod 
the other at the level of the pendulum bob. These thermometers were read 
five times a day viz. at 8 a.m., noon, 4 p.m., 8 p.m. and midnight. 
The scales were Reaumur’s and were divided into full degrees. 
We will first investigate the relation between the results given by 
the two thermometers. The readings of the years 1878, 1879, 1884 
and 1885 were discussed for this purpose. In the following table the 
monthly means of the differences between the two thermometers are 
given for each of these four years, after application of the index- 
corrections. The differences are taken in the sense upper thermometer- 
lower thermometer. The last column gives the means of the four years. 
| _ 4878 1879 1884 | 4885 Mean 
January ...., + 0.46 | +042 | +0419 | +0416 F+ 0.16 
February...) + 0.18 + 0 16 + 0 19 + 0 21 + 0.18 
Meirelins fects: + 0.20 | + 0.214 + 0.22 + 0.20 [+ 0.21 
Atrios mare [40.33 | +095 |+0.9% | +. 0:97 FH 0.97 
EE 0.28 | + 0.99 0.27 024 0.27 
Fay er | Ie +027 | 4-024 | 4- 0.27 
Tuer tara te, }+ 0.299 | +0. |H0% | 40.99 | + 0.98 
| | | | 
July.... ...| + 0.26 [40.4 | +025 [4028 | + 0. 
August. ...| + 0.22 | + 0.22 | + 0.27 + 0.25 | + 0.24 
September ..| + 0.21 | + 0.20 | + 0.92 | +092 |+ 0.91 
October..... +048 | + 0.149 | +0.20 | +0419 | + 0.49 
November...| + 0.16 | + 0.18 [ce 0:20 OS | or Oa 
December...) + 0.48 | +048 | + 0:48 | +0417 | + 0.16 
There appears to be a constant difference of about + 0°.2 between 
EEE 
