Survey of Northeast Greenland. 265 
well see to everything oneself. It is in such cases advisable to place 
the leather case of the instrument between the legs of the tripod, to 
place the watch here and read it off immediately after pointing the 
sun. It is of no importance that in this manner one will always 
come to read off the watch a few seconds too late; besides one can 
very nearly determine, by way of experiments, the loss of time in 
reading off the watch and reduce the clock time accordingly. 
Should one not be possessed of a watch, one may, in lieu of it, 
use the horizontal circle for this purpose’). 
Whether at determinations of latitude one points the upper or 
the lower limb of the sun is, as a rule, immaterial; only, as long as one 
is not very expert, one ought to be content to use the one limb. 
In the following I am going to give a few examples of what the 
instrument can do under the difficult arctic conditions. 
Latitude, noon 6/У 1907 (observed by Koch without an 
assistant). ©; b = 770 mm; t = - 14°C; velocity of the wind 6m; 
light snow drift. Instrument placed on snow-cowered sea-ice 5 to 
10km south of Kap Ejler Rasmussen. I — about 1730 w. of Grw. 
One division of the level = 20”. 
Telescope left | Telescope right 
| Vernier | Level | | Vernier | Level 
Clock time I— = — | Clock time | = - | Е 
РУ. B | Obs. | Obj. | | A: в | Obs. | Obj. 
u =. | ЕЕ | = ee === ЕВЕ 
11b34m00s | 293°38’.8 | 39.1 | 12.5 | 7.3 | 11h36m25s | 66°21'.6 | 22’.6 | 3.6 | 8.8 
39 00 | 39.1 | 39.5 | 12.0 | 6.8 | 40 50 | рб. 
42 55 | 392 |396 | 115/62 | 44 35 | 11 | 221 | 37| 88 
46 45 | 39.2 | 39.6 | 11.5 | 6.3 | 48 45 | 21.0, | 22:0. | 30 8.3 
50 45 | 392 | 395 | 120 | 6.7 | 53 10 | 211 | 221 | 30 | 82 
55 00 | 391 | 394 | 116 | 62 | 5700 | 212 | 222 | 30 | 82 
For the rough computation only the fourth pair is used, which 
judging by the readings is lying nearest to the culmination. 
Telesc. left.... 360° — 293°39'.4 = 66°20'.6 
Melese. richt’ RER Ge 66°21'.5 
Mean  66°21'.1 
Level + 0.5 
Refr. + 2 
eee) | 160 
9 1 10981 
ф = 82°%6'.2 
1) See A. Marcuse: Handbuch der geographischen Ortsbestimmung, Braunschweig, 
1905, p. 235. 
?) p + л = semi-diameter + parallax. 
ö = declination. 
