APPENDIX, 153 
territory along the western slope to occupy its attention in 
returning. 
Much of the ultimate importance and interest, as well as 
the security of guidance and prospect of safe return to the 
expedition, will of course depend upon our obtaining an 
exact knowledge, and preserving a faithful record of its route, 
which can only be done by the aid of astronomical observa- 
tions made with due regularity and precaution, not only at 
such stations as form the most interesting features at the 
moment, in the eyes of those concerned, but at every station 
where the expedition may rest long enough to permit obser- 
vations to be taken deliberately, and with due regard to the 
safety both of the observer and instruments. The track ofa 
caravan on land, as of a ship at sea, is defined, as well by the 
less, as the more remarkable points through which it passes ; 
and it may very easily happen, that stations of the highest 
interest in a commercial, political, or physical point of view, 
may, by reason of that very interest, be inappropriate for 
selection as principal observing stations, either from the 
attention of every individual being distracted to duties of 
immediate necessity, or from the risk attending the ex- 
hibitions of instruments in the unavoidable presence of a 
rude, curious, and suspicious population. In allsuch cases, 
it will be proper to connect, by observations of a less elaborate 
nature, those stations with others not far distant, which, 
although less intrinsically important, may be easier of exact 
determination. ‘The Committee would, therefore, recom- 
mend, that stations of observation be classed as either pri- 
mary or secondary. ‘Those to be considered primary stations, 
whenever the circumstances may appear particularly favour- 
able, by reason of leisure from other cccupations, expected 
duration of halt, and freedom from annoyance, to afford a 
good determination of the longitude and latitude, such as may 
