6io THE POPULAR SCIENCE MONTHLY 



I 



general trend of the less broken lava streams, we gradually worked up- 

 ward and inward toward the main axis of the whole lava mass, indi- 

 cated by vents which gave egress to steam and gases discharged by fluid 

 lava running through tunnels beneath the surface. 



The great crater (Fig. 3) is a perfectly typical cone of cinders and 

 lava, with a height from base to summit of four hundred feet as meas- 

 ured by the aneroid barometer. On three sides it is composed mainly 

 of ashes and pumice, but toward the sea its surface displays smoother 

 areas of rock where the lava formerly welled over the edge before the 

 tunnels were formed by which the discharge now takes place. Large 

 bombs, rounded masses of rock hurled from the crater during some ex- 

 plosive eruption, occur on the slopes, sometimes covered as by a sheet of 

 tar with a later-extruded layer of lava (Fig. 6). 



When we stood upon the extreme edge of the jagged margin and 

 looked down upon the immense lake of fiery lava, four hundred feet 

 below, it was hard to realize that the scene was actual and not an 

 imaginary panorama of Dantesque infernal regions. The yawning 

 cavity of the crater extended a full half mile in length, and its width 

 was more than four hundred yards. Almost perpendicular and some- 

 times undercut, the crater walls dropped hundreds of feet to the lake 

 of molten lava, which was in such violent commotion that it seemed to 

 be liquid flame rather than a mass of fused and fiery rock. At certain 

 places it boiled with greater activity, sending huge jets and fountains 

 high into the air. Its waves moved variously at different times, but ever 

 and again they would surge heavily to dash against the wall where the 

 tunnels opened to give exit for the flow to the ocean. And always from 

 this surface, thin steam-like vapor charged with acid gases swirled up- 

 ward in the draught caused by the strongly-blowing trade winds, ma- 

 king it excessively unpleasant to look over the edge even from the wind- 

 ward side. 



Magnificent though it was by day, the scene at night was far beyond 

 human powers of description. With the darkness, the lake glowed almost 

 as a continuous incandescent mass. Its light was reflected upon the 

 clouds above, making a beacon that we had often seen from a distance of 

 forty miles and which was said to have been visible at a distance of seventy 

 miles during the period of the volcano's greatest activity about two years 

 earlier. Looking seaward, the rosy vapors above the tunnel vents out- 

 lined the course of the lava down to the shore of the island where the 

 fire of the final lava cascades gave color to two huge clouds of steam. 

 Again and again through the night we climbed from our camp at the 

 base of the cone to look down upon the fascinating but awful marvel, 

 whose fires illuminated the scene so as to give ample light to guide a way 

 over the broken lava. 



Leaving now the volcano of Savaii, which is a veritable classic in its 

 regularity of structure and mode of origin, we pass to the Hawaiian Is- 



