541 
We now deduce the values of I, II, and Ul by comparing the 
individual results with their mean, first of all for the observations 
at Jidda and Mecca separately, afterwards for all together. In order 
to deduce in the latter case the values of Il (just as afterwards os 
IV) the general mean of the y, — pp (and later on of the py, — @g ) 
has been employed. The result was, however, practically the same 
when the two separate means were used. The first series of obser- 
vations at Jidda has been left out of account throughout this investigation, 
as it was less homogeneous and besides contained Mr. Sa.im’s first 
observations, when he had had little practice as vet. 
Jidda Mecca Logether 
PGE 10786)? = 117.96. (4 10". 91)? = 119.08 (410.887 = 116.44 
HCE: 967 == 93.59 (+ 8".30) 6940 E. 8.99)? Ss 80.74 
WSC LINE Sr 299 Ge 705) = 49.0 Ge 65.09)? Sen SHAD 
From this appears very satisfactorily that I] + III == 1, while we 
find in the three cases: 
UI (+ 8".10)? = 65.60 (+ 4" 44)? = 19.69 (+ 6".60)? = 43.61. 
We can now compare inter se the values of m and M. As the 
signals at Jidda and Mecca were of a different kind the two values 
of M must not a priori be accepted as equal. The differences found 
between the m and M for the two places are, however, evidently 
not real, and we may only conclude from the general results that 
m and M are about equal, only possibly M slightly greater than m, 
which wouid also a priori be probable. 
This investigation raises the question whether it would have been 
better to employ for the zenithpoint mean values from longer periods 
instead of the individual results, and although the value of the 
zenithpoint is generally eliminated, I still wanted to examine this. 
Therefore the observations have also been reduced with the zenith- 
point from the whole of the period in which the instrument remained 
at one station, and then the squares of the mean error I and IL 
have again been determined. As the last 3 isolated nights of observation 
at Jidda have not been used here, the values of I and II were also 
deduced again after the first way of calculation. 
Thus we found: 
Jidda Mecca Together 
With individual zenithpoints 
THAT OOP = 421.02: (He LOM 129-08: (-6 107.96)? = 120.06 
II (410.02)? = 100.45 G 8.33)? = 69.40 (+ 9.22) = 84.93 
With mean zenithpoints 
(090 OB GE 1105 130.54. CE 10S 0 LSB 
WES == (yen (EI 2) ==. 9619 (- AA == Sid 
