Survey of Northeast Greenland. 283 
suffers thereby; the observation lasts longer; the taction of horizontal 
thread and limb becomes less reliable, because one has at the same 
time to look to the vertical thread; in short, observations of time 
and latitude would by such a proceeding become less accurate. 
Below I shall give two examples of observations of azimuth, 
both from the most northerly station of the expedition at Kap Bridg- 
man (ф = 83°29'.3). The first observation which was taken imme- 
diately after the afternoon time observation (see pp. 273—274) could 
not be used, because the fog set in, before the directions at the various 
terrestrial objects had been measured. A second azimuth observation 
was made immediately after the midnight latitude (see pp. 267—268). 
The peak of a single mountain had, however, been pointed after the 
first observation of azimuth, and as the same peak was also sigthted 
immediately after the midnight observation, a comparison between 
the results is possible. г) 
For the final computation at home the following formulæ are 
used: 
tan ts a — == V sec a cos (a + =) sin (a + g) cosec (о +0), 
cota = BUG cost FR cos p tan 0 
sin ft 
At the introduction of the auxiliary angle M determined by 
tan М = tan 0 sect the latter expression is converted into 
tana — tan Ё cos M cosec (ф ~ M) 
The rough computation during the sledge trip is made by the 
sin f sin (90° = 
ee by means of the table on p. 263. 
sın Z 
formula sina — 
Kap Bridgman 15/V 1907. Afternoon. Determination 
| 
ofazimuth. Observer: Koch; Assistant: BERTELSEN; (); b = 769 mm; 
t = - 10.5; ф = 83°29.3; approximate clock correction to Grw. 
SGrw. = about + 1530™; local clock correction: $ = + 16™30s. One 
division of the level — 20”. Instrument placed on glare ice in the 
immediate vicinity of the coast. 
| | É Vernier в Level | : | 
Telescope VEN АС | оковы | = Samen 
| A | В |Obs.| Obj. | circle | 
Compass 
Ш 
TEE | gng2mg2s | 28899974 | 23.1 
| | | ти Ir u Fe 
| 11.8 | 60 | 346°02° | 153°.7 | 152°.7 
right ...... | 34 32 71418 | 424 | 50 11.0 | 346% | 
| | | |] | 
| Peak No. 42. | 311°41’ 
1) As the azimuth during the first observation was conveyed to a peak it seems 
superpluous to undertake a new determination of azimuth, when the fog lifted. 
Why we did it I do not know. 
