ON THE TOLCANIC PHENOMENA OF VESUVIUS. 



287 



cone. Siraaltaneously the eruptive cone which had now reached great 

 bulk, and a height of 40ni. to 50ni., commenced to fall in consequence 

 of the failure of support from the lava sinking in the chimney, and 

 pouring out through the lateral opening. In about one hour great 

 progress had been made in reducing the cone of eruption to the state of a 

 crater-ring of very considerable dimensions. The outpour of lava had 

 carried forwards the fragments of the crumbling fissure sides so as to 

 leave a chasm 20m. to 30m. wide, along the bottom of which the liquid 

 rock continued to pour, dividing into two streams when it reached the 

 crater plain of the Atrio del Cavallo. 



My friend Mr. G. P. Bidder, who was able to visit the seat of eruption 



Fig. 4. — Diagram of the Summit of the Great Vesuvian Cone, May 1, 1889, 



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" L<wa/ of Jem,. €"^188!*. 

 Lettering as in former Figures. 



the following day, found a very considerable outpour of lava, but the 

 progress slow, and the surface much covered by scoria, showing that the 

 first outrush had terminated. Notwithstanding much cloud, a strong 

 reflection from the flowing lava could be seen in the evening. 



The rift produced in this disruption is but a few yards to the N". of 

 the old one that has allowed the lateral draining of lava to occur from 

 1881-2, and several other times during the last eight years. There is 

 little doubt that the radial dyke which caused the 1881-2 eruption has 

 never completely solidified. 



The lava was still fairly high in the chimney, as I noticed one faint 



