PILLARS OF SAND IN THE DESERT. 263i 



noticed the rooks and some of the minerals met with in the 

 Desert, we shall next attend to the sand of which, it is 

 principally composed. The loose alluvial matter which 

 forms the sand of the Desert is principally composed of 

 particles of white and gray quartz of various sizes, gene- 

 rally very small, forming the sand, properly so called, seldom 

 so large as to form gravel and pebbles. Some are of opi- 

 nion that this sand is an original deposite ; others, that it is 

 fonned from previously existing rocks through the agency 

 of water. 



Moving Pillars of Sa7id in the Desert. — During the storms 

 that often rage in this Desert, the sand is raised into clouds 

 that obscure the horizon, or it is by whirlwinds raised into 

 pillars. Bnice describes an appearance of this kind, which 

 he witnessed in his journey through the eastern part of 

 the Desert, in his route to Abyssinia, in the following terms : 

 • — " At one o'clock we alighted among some acacia-trees at 

 Waadi-el-Halboub, having gone twenty-one miles. We 

 ■were here at once surprised and terrified by a sight, surely 

 one of the most magnificent in the world. In that vast ex- 

 panse of Desert, from west to north-west of us, we saw a 

 number of prodigious pillars of sand at different distances, 

 at times moving with great velocity, at others stalking on 

 with majestic slowness. At intervals we thought they were 

 coming in a very few minutes to overwhelm us, and small 

 quantities of sand did actually more than once reach us ; 

 again they would retreat, so as to be almost out of sight, 

 their tops reaching the very clouds ; then the tops oflen sepa- 

 rated from the bodies, and these, once disjoined, dispersed 

 in air, and did not appear more ; sometimes they were broken 

 in the middle, as if they were struck with large cannon- 

 shot. At noon they began to advance with considerable 

 swiftness upon us, — the wind being very strong at north. 

 Eleven ranged alongside of us, about the distance of three 

 miles ; the greatest diameter of the largest appeared to me 

 at that distance as if it would measure ten feet. They 

 retired from us with a wind at south-east, leaving an 

 impression on my mind to which I can give no name, 

 though surely one ingredient in it was fear, with a con- 

 siderable deal of wonder and astonishment. It was in 

 vain to think of flying ; the swiftest horse would be of no 



