FLOATING PUMICE-STONE. 67 



them, remarkable for its more limited cir- 

 cumference but greater elevation, is shaped like 

 a gunner's quoin, and rises as an amphitheatre, 

 luxuriantly wooded to the water's edge. 



The surface of the sea in this strait, was 

 covered with vast quantities of pumice-stone, 

 floating in small pieces, rounded by attrition. 

 Some of them were black, others of an olive-gray 

 colour ; and it is remarkable, that the specific 

 gravity of many of them was so nicely balanced, 

 that although they floated in the sea, they sank 

 when placed in fresh water. Their origin is due 

 to the volcanic islands of this Archipelago : the 

 volcanic mountain of Ternate is often in action ; 

 and as late as the year 1836, South- Seamen 

 cruising in the straits of Timor, were compelled 

 to keep their decks wet, on account of the 

 showers of hot ashes thrown upon them during 

 a volcanic eruption on the Island of Flores.* 

 Such collections of pumice-stone on the surface 

 of these seas are not uncommon ; and are oc- 

 casionally so great, that ships have had their 

 copper brightly polished by passing through 

 them. 



* To the same cause may be attributed, the origin of 

 those large porous stones occasionally found floating on 

 the sea, to the great surprise of navigators. 



F 2 



