Feb, 21, 1878] 



NATURE 



327 



the weather was so bad at the time that the collections 

 made were not numerous. 



In June, 1871, the English frigate MegcBra was wrecked 

 on this island and most of the 400 souls that were aboard 

 her had to reside on it for over three 

 months. 



On September 30, 1874, the mem- 

 bers of the Transit of Venus expedi- ^_,.^ 

 tion landed on St. Paul and spent 

 thereon over three months. 



Both the islands are essentially 

 volcanic. In 1696 when van Vlaming 

 visited St. Paul, the vast crater occu- 

 pied its central part, and was above 

 and quite isolated from the sea, and 

 it seems to have been even thus in 

 1754, ^^^ ^^ present the sea flows 

 freely into it, and at the place of com- 

 munication there is a depth of upwards 

 of six feet. It attains a height of 

 about 250 metres and its contour line 

 is not much more than five nautical 

 miles. A little to the north of the 

 entrance to the crater where the sea 

 has broken in there is a wonderful 

 piijnacle of basaltic lava, which re- 

 ceives the name of the Ninepin rock 

 (Fig. i). The rocks composing it are 

 trachitic, of a compact texture, but 

 more or less zoned. These rocks, 

 full of silex, and poured forth in great 

 measure under the sea, exhibit still 

 the traces of the energetic alterations 

 which they underwent, not only at 

 the moment of their emission, but also 

 after their complete solidification^ for they have been 

 traversed since their formation in every way j not only 

 numerous fissures forced up by the impetuous escape of 

 gaseous emanations but by the force of geysers, which 

 latter considerably increased the amount of silex on the 

 rock, and this so much so that the 

 walls of such fissures through the 

 trachytic rock are formed of a very 

 able solid enamel of silex which is 

 rarely hollow, and all the alkalies have 

 totally disappeared. A microscopical 

 examination shows, amid a highly 

 developed -amorphous paste, crystals 

 of felspath, and pyroxene, with notable 

 quantities of silex, amorphous (opal) 

 or crystalline (tridymite) ; but the 

 lavas of different periods of eruption 

 seem to differ in their compositions. 



A wonderful core of basalt columns 

 is to be seen at the little North Island 

 (Fig. 2) which consists of little else 

 than columns, though many of them 

 are now thrown down. Some of the 

 more compact of the lavas present a 

 more or less picturesque outline, as 

 can be seen at Hutchinson Point 

 (Fig. 3), towards the south-east of the 

 island. Their endurable and adhesive 

 glissades could alone furnish such 

 needle-shaped projections as would 

 be capable of resisting the extreme 

 and never-ceasing violence of the seas "^'i'^i '••-' 



that beat on them. Along with the 

 basaltic lavas, there will be found 

 here and there on their upper sur- 

 faces little cones of scoriae thrown up from little supple- 

 mentary volcanoes ; sometimes these will be found here 

 and there quite isolated, at other times they will be 

 found forming a ring as it were around the principal 



crater. They form a record of the fact that long after 

 the great original outburst that formed this island there 

 were numerous smaller eruptions, and that the source 

 of volcanic power endured for a considerable time. 



Fig «.— North Island. 



Although at the period of Lord Macartney's visit (1793), 

 Dr. Gillian remarks that there were spots on the island too 

 warm to walk on, yet there is not a trace of recent volcanic 

 action to be now felt or seen, except in the interior of the 

 crater. M. Velain informs us that the botanical collec- 





Fig. 3. — Lava Cliffs — Hutchinson Point. 



tions made will be fully described by Dr. de I'Isle (from 

 fifty to fifty-five species, not counting algas, were found), 

 and that the rich and large collections of marine animals, 

 including fish, Crustacea, Echinoderms, Ascidians, Hydro- 



