556 
I + 283218 (es 
Il 33.80 (+ 1.85) 
Ill 33.92 (+ 1.58) 
IV 34.23 (+ 1.73) 
V 34.38 (+ 1.47) 
The mean errors in brackets have the same meaning as above ; 
in solutions IV and V they refer to observations with weight unity. 
Of all these solutions the 5 seems to me certainly to be preferable. 
I have, however, communicated also the other results, since they 
show the influence of the different ways of treating the observations. 
On the other band I shall not give the results of a discussion of 2 
successive journeys to Mecca together. The thus obtained formulae 
do not represent the observations better than the formulae deduced 
‘from the 3 journeys together. 
The final result for Dent 2527 I should like to deduce as follows: 
The 3 journeys J.—M.—J. 1st meth. + 2m 35826 
22d meth. 34.72 
Mean + 2m 34-99 
The 2 journeys M.—J.—M. =f 2 34.73 
Mean et gm 34586 
General solution +2 34.38 
Adopted final result + 2™34°62 
(To be continued). 
Astronomy. — “Determination of the geographical latitude and 
longitude of Mecca and JSidda executed in 1910—11.” By 
Mr. N. Scnervrema. Part III. (Communicated by Prof. E. F. 
VAN DE SANDE BAKHUYZEN.) 
(Communicated in the meeting of September 28, 1912). 
6. Derivation of the difference of longitude Jidda- Mecca. 
(Continued). 
be Watch NSE 7. 
Watch N°. 7 was taken on the 2nd and 3rd journeys to Mecea. 
During the whole period of the observations it clearly showed a 
progressive acceleration. Any direct influence of the transport, how- 
ever, was not clearly visible; nor was this so much to be feared for our 
earefully transported pocket-chronometers as for the box-chronometer 
of Dent. 
