1898-1902. No. 4.] ASTRON. AND GEODET. OBSERVATIONS. 7 



Gaase Fjord and adjoining districts were triangulated during the 

 summer of 1902, starting from a repeatedly measured base-line of 1500 

 metres, on the ice of the fjord. 



In this triangulation, azimulhs were taken northwards to Bear Cape 

 Land (Bjornekaplandet), and southwards — as already mentioned — to 

 St. Helena and other points. This connects the most northerly and 

 westerly points of our region with those farthest south and east, all 

 being based upon the geographical position of the winter haven. This 

 was the main purpose of the triangulation, during which trigonometrical 

 measurements of altitude were also made. 



The mode of travelling in arctic regions makes altimetry difficult. 

 Most of our altitudes have been obtained by reducing readings of pocket 

 aneroid barometers. The error of these instruments, however, under- 

 went great changes, owing to the rough treatment to which the driving 

 with dogs in arctic regions subjects, them. 



In addition to barometers, we had with us, as a rule, other instru- 

 ments for hypsometric measurements; but, as already indicated, no small 

 proportion of our altitudes were measured trigonometrically. 



During the winter months, our observations were worked out, and 

 maps were constructed and drawn (principally on Mercator's projection). 

 Great assistance in calculating was afforded by Bcrgen's tables on 

 Mercator's function (see Prof. C. Borgen, "Ueber die Auflosung nautisch- 

 astronomischer Aufgaben"; Hamburg, 1898). These were moreover easily 

 carried on expeditions, as they numbered only ten pages. 



All our measurements were made in low temperatures, from a few 

 degrees of heat down to about 50° G below zero. There were therefore 

 difficulties connected with the work, and not infrequently as a conse- 

 quence of this, a whole series of observations had to be rejected, or the 

 observations repeated. 



Some of us, too, might have something to tell of the difficulty of 

 carrying on this kind of work with eyes that are strained with a bright 

 sun and reflected light. 



