i 9 i i] ON ARCTIC SURVEYING 3" 
ought to have in his memory the approximate variation of 
the compass at various stages of the journey and to know 
how to apply it to obtain a true course from the compass. 
The variation changes very slowly so that no great effort 
of memory is required. 
2. He ought to know what the true course is to reach 
one depot from another. 
3. He should be able to take an observation with the 
theodolite. 
4. He should be able to work out a meridian altitude 
observation. 
5. He could advantageously add to his knowledge 
the ability to work out a longitude observation or an 
ex-meridian altitude. 
6. He should know how to read the sledgemeter. 
7. He should note and remember the error of the watch 
he carries and the rate which is ascertained for it from 
time to time. 
8. He should assist the surveyor by noting the 
coincidences of objects, the opening out of valleys, the 
observation of new peaks, &c. 10 
Tuesday, June 13. — A very beautiful day. We revelled 
in the calm clear moonlight ; the temperature has fallen 
to -26 0 . The surface of the floe perfect for ski — had a run 
to South Bay in forenoon and was away on a long circuit 
around Inaccessible Island in the afternoon. In such 
weather the cold splendour of the scene is beyond descrip- 
tion ; everything is satisfying, from the deep purple of the 
starry sky to the gleaming bergs and the sparkle of the 
crystals under foot. 
