224 
our journey at half past two in the morning in a west- 
ward direction, over a plain of coarse sand mixed with 
calcareous pebbles. At seven o'clock we passed among 
the hills which enclose the country, and at half past ten 
descended into another plain. 
The heat was dreadful. During more than an hour 
I felt the singular phenomenon of a continual current of 
wind from the west, alternately h%t and cold. If it had 
blown in gusts, I should not have been surprised at the 
circumstance, but it was an equable and continued cur- 
rent with intervals of heat and cold, so rapid and violent, 
that frequently in the space of a minute I experienced 
twice or thrice alternations of piercing cold and burn- 
ing heat. How is it that the caloric was not reduced to 
an equilibrium, with the mass of the ambient air? 
I now took the lead with two servants and my guard 
mounted upon dromedaries, and continuing along the 
same plain, bounded to the left by a range of hills, and 
to the right by a number of dunes, or mounts of moving 
sand. I arrived at Alberca at half past one in the after- 
noon: the rest of the caravan arrived two hours later. 
Alberca, called by the Turks Berket el Hadj, or the 
well of the Pilgrims, is a village composed of about 100 
families, and in so delightful a situation, that, upon 
leaving the desert, it appeared to me finer than Ver- 
sailles or Aranjuez. The overflow of the Nile arrives 
here by a canal. The village is situated on a hill under- 
mined by waters, which may be obtained at two 
fathoms depth. The hill and the plai . are covered by 
palms, very thickly but regularly planted. The ascent 
to the village forms a broad and delightful path, re- 
freshed by the water, and shaded by lofty palm and 
other trees. At the foot of the hill is a superb fountain, 
iu an ancient mosque, which is now falling to decay. 
