204 LIGHT SCIENCE FOR LEISURE HOURS. 



Of the eruptions wliich have disturbed Vesuvius 

 during the last two centuries, those of 1779, 1793-, and 

 1822, are in some respects the most remarkable. 



Sir "William Hamilton has given a very interesting 

 account of the eruption of 1779. Passing over those 

 points in which this eruption resembled others, we 

 may note its more remarkable features. Sir William 

 Hamilton says, that in this eruption molten lava was 

 thrown up in magnificent jets to the height of at least 

 10,000 feet. Masses of stones and scoriae were to be 

 seen propelled along by these lava -jets. Vesuvius 

 seemed to be surmounted by an enormous column of 

 fire. Some of the jets were directed by the wind tow- 

 ard Ottajano ; others fell on the cone of Vesuvius, 

 on the outer circular mountain Somma, and on the 

 valley between. Falling, still red hot and liquid, they 

 covered a district more than two miles and a half wide 

 with a mass of fire. The whole space above this 

 district, to the height of 10,000 feet, was filled also 

 with the falling and rising lava-streams ; so that there 

 was continually present a body of fire covering the 

 extensive space we have mentioned, and extending 

 nearly two miles high. The heat of this enormous 

 fire-column was distinctly perceptible at a distance of 

 at least six miles on every side. 



The eruption of 1793 presented a different aspect. 

 Dr. Clarke tells us that millions of red-hot stones were 

 propelled into the air to at least half the height of the 



