COMPLETION OF THE ROUTE. 91 
after they had staid with us three days, we had the satisfac- 
tion to see them depart, and to be delivered from their 
troublesome company. 
At four in the evening we encamped to pass the night, 
during which we were oppressed by excessive heat, caused 
by a dead calm. The sky was heavy and covered with clouds 
which seemed immoveable in the immensity of space. Still 
the heat continued intense. 
Before proceeding farther, I ought to inform the reader 
how 1 continued to make an estimate of the route. We 
travelled, at an average, about two miles an hour. At night 
we proceeded almost constantly in a northerly direction. 
Being afraid that my pocket compass would be noticed if I 
took it out to consult it, I judged of our course during the 
day by the sun 5 in the night, by the pole-star. 
It is by this star that the Arabs are guided in all their 
excursions through the desert. The oldest caravan con- 
ductors go first, to lead the way. A sand-hill, a rock, a 
difference of colour in the sand, a few tufts of herbage, are 
infallible marks, which enable them to recognize their situa- 
tion. Though without a compass, or any instrument for 
observation, they possess so completely the habit of noticing 
the most minute things, that they never go astray, though 
they have no path traced out for them, and though the wind 
in an instant completely covers w^ith sand and obliterates the 
track of the camels. 
The desert, however, does not always present the same 
aspect, or, consequently the same difficulties. In some parts 
I found it covered with rocks and gravel, which bore the 
traces of caravans that had passed long before. Besides, 
though the desert is a plain of sand and rock, the Arab 
commits few errors in crossing it, and is seldom wrong to 
the extent of half an hour in fixing the time of arrival at 
the wells. I ought not to omit to mention, that these 
wells are almost constantly found covered over, and that 
