( 404 ) 
and for the mean of all £1".9. If we add to this as mean error 
of the index correction + 8".3 X y1/; = + 3".7, the total mean 
error becomes + 4".1. The uncertainty in the correction of the 
chronometer may be perhaps a little larger than for May 10, 1893, 
although the acceleration found after May 22 has probably not begun 
before that date, about which time the colder season began. But 
at any rate, through the symmetrical arrangement of the observations, 
an error of this kind will influence only very slightly the final result. 
In reality the observations for index error will as a rule be 
preciser than the altitude determinations with the mercurial horizon 
and, if on the other hand we take into consideration the possible 
uncertainty of the chronometer correction, then I don’t think the 
precision of my observations is overrated, if we assume + 5" as mean 
error both of the result of May 10 1893 and of that of May 14,1894. 
3. Meridian altitudes of the sun and of «@ Crucis. 
In the third place I measured several times the greatest altitude 
of the sun and once that of @ Crucis. 
The observations on the sun were always made on the lower 
limb, as in this way the maximum altitude from the mercurial horizon 
is easiest and most accurately measured; the images of the lower 
limb namely are separating before the culmination. 
Here follow the observations and their results. The column 
„Corr.” gives the sum of the index correction and the correction 
for errors of graduation. ‘The declinations and the semidiameter and 
parallax of the sun were taken for 1893 from the Connaissance des 
Temps, for 1894 from the Nautical Almanac. 
Date. Object. Reading. Corr. Temp. | Barom. | Latitude. 
ae | 
May 7 1893 | Sun L. L. | 129° 56'50'| — 1/30" | 29° 759.5 be 7 50’ GNF 
7 8 z r ” 129 24 20 | 1 30 | 29 758 50 4.4 
” 9 7 ” 2 128 52 20 | 1 30 28 759 50 4.2 
„ 10 w w 7 128 -21 0 1 30 27 760 50 146 
June 2 w "i 5 119 20 15 | Les 27 761 60 abt 
May 10 1394 | « Crucis. 70 42 O 1 13 25.5 760.4 50-326 
i ge aE a Sun L. L. | 126 28 20 1 30 27 | 760 49 57.0 
The results from the altitudes of the sun still remain to be cor- 
