HARDWICKE'S SCIEN CE-GOSSIP. 



221 



pendicular, others more or less horizontal, and 

 intersecting one another at all possible angles. 



From the Atrio upwards the really hard climb- 

 ing begins, up the steep cone, with its loose blocks 

 of scoricB and lava interniingled with fine loose ash. 

 When the summit is nearly gained, the topmost 

 part has from a little distance the appearance of 

 soft bright green grass, which a closer inspection, 

 however, proves to be sulphur and its compounds, 

 all smoking away like a huge dunghill. 



All around is spread a magnificent prospect. 

 Immediately below lies the Atrio, just above which 

 may be clearly seen the three small craters which 

 gave rise to the lava of 1S58 ; the current itself may 

 be traced running from them against the walls of 

 Somma, then turning to the west, in which direction 

 it is hidden for some short distance by the more 

 recent flows of 1S67 and 1868, and again appearing 

 with its ropy structure, south of the Salvatore 

 ridge ; shorter currents from the same craters are 

 also seen running eastwards, farther into the Atrio. 

 Beyond, frown the steep and lofty cliffs of Somma, 

 a little to the west is the ridge of San Salvatore, a 

 fragment of old Somma, standing up amid black 

 lava-flows (1855 and 1SC8 on the north, and 1767, 

 1858, and 1867 on the south). Farther off lie, 

 the plain, with scattered towns and villages, sur- 

 rounded by green vineyards, the beautiful bays of 

 Naples and Baise, the islands of Ischia and Procida, 

 the old volcanic mountains of the Phlegraian Fields ; 

 and farther otf still, bounding the fertile plain and 

 mai-king an old sea-coast, are the higher mountains 

 beyond Capua and the snowy Apennines. Turning 

 from this magnificent prospect, the crater-edge is 

 gained : the sides are seen to slope steeply inwards, 

 but the volumes of smoke constantlypassing upwards 

 hide the structure of the interior, except for momen- 

 tary glimpses. Leaving the edge of this great 

 smoking caldron, some small holes attract attention, 

 holes not more than a yard or so wide, but of un- 

 known depth, up which is constantly ascending a 

 powerful current of hot air, so that fine sand or 

 fragments of paper thrown in are at once blown 

 forcibly out. 



Passing round the edge of the crater, a view to 

 the south is obtained; the plain on which Pompeii 

 stood lies directly below, bounded by the mountains 

 behind Castellamare, again forming the boundary 

 of the old sea before mentioned. Across the blue 

 waters of the bay the hills behind Sorrento and the 

 island of Capri please the eye by their soft outline 

 and delicate tint, while black lava-flows form a well- 

 contrasted foreground. On the south-east side 

 another flow of the 1867 lava can be traced ; while 

 those of 1850 and 1834 run also to the south or 

 south-east, and, far below, the red craters of 1760 

 are conspicuous. Having about completed the cir- 

 cuit of the crater, the descent upon the south-west 

 side is very instructive. The first part is made very 



rapidly, plunging up to the knees in fine black ash 

 (which near the summit is quite hot below the sur- 

 face), accumulated about and among the lava-flows 

 of 1834, &c. In this easy manner about half the 

 height of the mountain is descended in a very short 

 time. The ash is for the most part very fine, and 

 on examination is found to contain many separate 

 crystals of leucite and augite. The several little. 

 red craters of 1794 are now reached; small model 

 craters, at present very shallow, all close together, 

 and one of them double ; the birthplace of the lava- 

 stream which destroyed Torre del Greco and ran far 

 out into the sea. Just above these might be ob- 

 served the sudden termination of a much more 

 recent stream, presenting the appearance of a low line 

 of steep cliff; and far below, only just above Torre 

 del Greco, may be noticed the eleven little craters 

 opened out along a straight line in 1861, and which 

 again threatened the town with destruction. 



Soon after leaving the craters of 1794, the region 

 of vineyards is once more gained, not before passing, 

 however, signs of their former higher extension, in 

 the shape of ruined huts enveloped in lava yet not 

 overthrown. Sometimes a wall of lava may be seen 

 approaching within a foot or so of a hut, which it 

 may partly surround, yet not overthrow. It seems 

 that such an elastic resisting cushion of hot air is 

 entrapped between the hut walls and the lava, as 

 to resist the progress of the latter for some time, 

 though finally it usually curls over the summit of 

 the dwelling and envelopes all. 



As regards the character of the Vesuvian pro- 

 ducts, both lava and ashes, a good deal of variety 

 is exhibited. There are the trachytic tuffs of earlier 

 erup tions associated with leucitic lavas or grey stones ; 

 there are basalts of modern eruptions, crystals of 

 augite in a dark matrix ; and there are modern leu- 

 citic lavas. So that we have the thi-ee classes of 

 volcanic rocks represented. 1st. Trachytic, essen- 

 tially felspathic. 1 2nd. Basaltic (Doleritic), mixture 

 of felspar and augite, the latter predominating : the 

 augite is often crystallized out in a compact base, 

 formed of mingled felspathic and augitic matter. 

 3rd. Greystones, an intermediate class formed of 

 felspar (or one of its varieties) and augite : in the 

 greystones of Vesuvius leucite takes the place of 

 felspar, and is frequently crystallized out in a dark 

 augitic base. J. Clifton Wahd. 



WooD-BOEiNG Insects. — There is nothing per- 

 haps in nature more wonderful than the sudden ap- 

 pearance and disappearance of these minor works 

 of the Creator, which are at his command called 

 forth to answer ends that our limited understand- 

 ings cannot comprehend, and whicii, being accom- 

 plished, are, by a combination of circumstances no 

 less wonderful, swept away from us altogether for 

 a season. — Curtis, "British Entomotogy." 



