ADEN. 119 
difficulties in which the subject is involved will permit, but as the 
deception affects the visible horizon and other objects on the 
earth's surface, it seems to merit a still more strict investigation, 
as it produces great incorrectness, particularly in warm latitudes, 
with respect to all observations taken by means of the visible 
horizon, as well as in those geometrical admeasurements which 
depend on a distant object, and are to be ascertained with a 
theodolite, or other instrument on shore. On this account an 
artificial horizon possesses decided advantages over the visible 
one in point of accuracy, and is;, whenever it can be used, to be 
greatly preferred.* 
In the evening, the Captain having completed his stock of 
water, a precaution which it is advisable for every ship to take 
at this place previously to entering the Red Sea, I returned 
to the Marian, after having had the trouble of settling my account 
with the Banians. Though these traders possess a remarkable 
suavity in their manners, and an immoveable command of temper, 
yet there are no individuals in the world more keen, artful, and 
rapacious in their dealing, and consequently in all communica- 
tions with them undue exactions must be expected and carefully 
guarded against, notwithstanding there may be an appearance of 
minute and scrupulous accuracy in their accounts. This may gene- 
rally be best effected by mild behaviour, yet unalterable steadiness 
in resisting their impositions. With respect to other points of 
character, I have been induced to think, from what I have witnes- 
sed, that they are a quiet, and estimable people ; and even in that 
point, which I have seen reason to condemn, some allowance 
* I am informed tliat a very satisfactory explanation of the various effects of refraction 
has been given in the Philosophical Transactions by Dr. Wollaston. 
