130 I. P. Косн. 
Poles. The extension east-west corresponding to u = 254 is at the 
latitude of Danmarks Havn (cos ¢ == 0,23) 
u — 256 metres 
1 
which perhaps gives а better idea of the accuracy arrived at. 
The uncertainty is, as will appear, rather great. Even if the 
accuracy is sufficient for all practical purposes, it would, however, 
be desirable to carry it considerably farther, in view of its importance 
to scientific research. It is to be supposed that something is to be 
gained by using a portable transit instrument (moon culminations), 
but fully satisfactory results will hardly be arrived at in Greenland, 
till telegraphic communication (wireless) has been established. 
Determination of Latitude. 
The method which is most suitable for a more accurate deter- 
mination of latitude under high arctic conditions is, as far as I know, 
the measurement of the zenith distance in the meridian shown by 
Colonel von STERNECK. 
A nearly equal number of stars south and north of the zenith 
are observed, and in such a manner that the sum of the zenith dis- 
tances measured on either side becomes nearly alike. Every star is 
observed only once during the same night, that is in the meridian, 
which must thus be fairly well known. In this manner the zenith 
distance of every single star is only to the obtained under the 
presumption that the zenith point of the circle is known. This is, to 
be sure, never the case with sufficient accuracy, but it is of no 
importance, as one arranges things in such a manner that the error 
of the zenith point is eliminated when determining the final results. 
In case a star is observed, for instance with “telescope west”, and 
if the latitude 6% is computed on the strength of this, irrespective 
of the unknown reading æ for the zenith point, then the real latitude 
will, apart from errors of observation, be @»-+ 2x. If then another 
star is observed with “telescope east”, the latter gives in the same 
manner the latitude ve + x, so that the mean gives the latitude 
independent of the zenith point, provided the latter was constant. 
The manner of proceeding is to observe a nearly equal number 
of stars in both instrument positions, at first irrespective of the fact 
whether the stars culminate towards the north or towards the south. 
The justification of this is that the zenith distance enters into 
the latitude with opposite signs for southern and northern stars 
(ф = 25 + ds and ф = д + Zn ог ф = 180 + (д. + Zn)). If only two 
stars are used, a southern and a northern one, and if the reversal 
