86 MEMOIR OF BURCKIIARDT. 



iiig in those tornadoes, are tales invented by the 

 Bedoains to frighten the townspeople. " In the 

 Simoom at Esne," he remarks," the thermometer 

 mounted to 121° in the shade ; but the air seldom 

 remains longer than a quarter of an hour in that 

 state, or longer than the whirlwind passes. The 

 most disagreeable eflfect on man is, that it stops 

 perspiration, dries up the palate, and produces great 

 restlessness." 



He notices another phenomenon of the desert, 

 which they encountered on the fourteenth day of 

 their journey. " During the whole march we were 

 surrounded on all sides by lakes of mirage (mist), 

 called by the natives soral. Its colour was of the 

 purest azure, and so clear, that the shadows of the 

 mountains which bounded the horizon were re- 

 flected in it >vith the greatest precision, and the 

 delusion of its being a sheet of water was thus ren- 

 dered still more perfect. I had often seen the 

 mirage in Syria and Egypt, but always found it of 

 a Avhitish colour, rather resembling a moving mist, 

 seldom lying steady on the plain, but in continual 

 vibration ; but here it was very different, and had 

 the most perfect resemblance to water. The great 

 dryness of the an* and soil in this desert, may be the 

 cause of the difference. The appearance of water 

 approached also much nearer than in Syria and 

 Egypt, being not more than two hundred paces 

 from us ; whereas I had never seen it before at a 

 distance of less than half a mile. There were at 



