No. 6.] INTRODUCTION. CHRONOMETERS. XLVII 
10. Increase of brightness very slow. 1.™4 later Sat. tolerably bright. 
11. Calculated time for D 2h 17™ 42s. Observed continually till 2h 28m, but no de- 
crease of brightness perceptible. Ceased for a while, but between 2b 42m and 
Qh 45m Sat. as bright as before — after which we left the Satellite to its fate. 
12. Calculated time for D Hw 20h 6™5s. Observed til 20 10™, unchanged, some- 
what feebler than the other Satellites. Calculated time for R Hw 21h 16m 99s ; 
observed 21h 114m—20m, but no inerease of brightness. 
13. 26s later brightness estimated as 40s before the moment noted for D. At 24h34m 
27s the Sat. approached to the usual brightness. 
14. First glimpse. 1™ 33s later same brightness as the Satellite to the left of Ju- 
piter [Sat. IV]. 
15. Had just moved the telescope; as soon as it had come to rest, the Sat. was seen. 
16. Observation begun at 14h 3m, 
17. Waited for R till 12h 40m, but Sat. not visible; cirrostratus. 
Influence of Temperature. 
As there were in each of the three years of the expedition periods of 
several months without any determination of the Greenwich Time, it was 
necessary to examine the general rate of the chronometer and its dependence 
on temperature. For this purpose the two other chronometers must also be 
taken into consideration. From the journal of daily comparisons the following 
Table d was formed, containing the difference At—Hw and Jv—Hw together 
with the daily relative rate of each. The last column (é) gives the mean 
temperature (Centigrade) of the interval. From the curves registered by the 
thermograph in Mr. Scott-Hansen’s cabin the mean temperature for every day 
was taken out by inspection and reduced to the chronometer-shelf by means 
of the daily comparisons with the lower thermometer. The temperatures in 
Table d are means for 10 days (the intervals between the comparisons are 
in some few cases 9 or 11 days). As the thermograph was taken down 1896 
Aug. 10 the temperature for the last 11 days is more uncertain. 
