252 Jordan on I he Tl out age uf\ 



It was an Egyptian darkness that might be felt. The dust 

 continued to increase, and fell in such large quantities as to cover 

 every thing to the depth of more than an inch, and even to 

 break down the branches of trees by lying on them. Between 

 twelve and one o'clock in the day, a vertical shadowy light 

 began to appear, the passage of light from the atmosphere 

 above being shortest in that direction through the dust, in a 

 circular form, which, as the dust thinned away, or drove 

 on, increased in diameter, until the whole body of particles 

 passed away visibly. By the impalpable particles of dust thus 

 deposited, for many days men and animals were grievously 

 annoyed; even the tender leaves of plants were injured, and 

 the wind agitating the dust, the whole face of the country 

 showed like the crater of a volcano. The volcano of St. Vin- 

 cent's had burst out. The dust thrown by the explosions to 

 considerable heights had, by the higher currents of air spoken 

 of, been carried to windward during the night, and, descend- 

 ing into the lower regions of the atmosphere, was drifted back 

 over the island by the ordinary trade wind a little to the north 

 of east. During the fall, patterings on the roofs of houses, as 

 of grosser particles than dust, were repeatedly heard, and 

 some of the dust sent to me contained particles of stones, 

 whose dimensions seemed to exceed all the power of floatage, 

 so gross that I was led to conceive that they were carelessly 

 taken up from the soil on which the dust lay. Other portions 

 of dust were free from these. 



An analysis of this dust in the laboratory of the Royal Insti- 

 tution, by Mr. Faraday, gives the following components : — 



Silex .• 78, 



Alumine 11^2 



Lime 7 



'j 



Oxide of iron 3^4 



Loss ^4 



100 

 This floatage power of small bodies may account for the dust 



