THE ZONE OF MAXIMUM TEMPERATURES. 375 



A few words upon the sun temperatures must not 

 be omitted. Throughout the Desert Zone, the solar 

 rays seem to acquire their maximum intensity; and 

 it would be perhaps hardly possible by a mere 

 verbal description to convey an adequate idea of 

 their power : the nearest approach to it being* probably 

 experienced when visiting an iron foundry, upon the 

 opening of the furnace doors ; indeed, the simile " like 

 the breath of a furnace " seems to be the regulation 

 metaphor adopted by most writers for expressing their 

 idea of the intensity of these desert heats, and it is 

 notorious that the highest temperatures in the world 

 have been registered in these regions. The scorching 

 effect of the sun's rays in a perfectly dry atmosphere 

 is a matter which has already been commented upon 

 and explained in the chapter on " Climates and Tempera- 

 tures," so that it will be unnecessary to discuss that 

 view of the question at present. 



The exceeding transparence and purity of the desert 

 air, of course, afford full scope for the transmission 

 of heat, and the refraction from the bare sand and 

 stones also greatly contributes to magnify its scorching 

 effects to a degree that becomes well nigh insupport- 

 able ; it is one of those things in fact which must be ex- 

 perienced in a man's own person before its fiery 

 intensity can be fully realized. 



All rock, stones and metal work, such as gun barrels, 

 etc., become so exceedingly hot, under its influence, 

 that it is impossible to lay the naked hand upon them, 

 and the feet appear to be treading upon heated embers, 

 or rather as if wading in a sand furnace; * lucifer 

 matches also can be lit by touching the sand with them, 



* Desert Life, by B. Solymos, 1880, p. 17. 



