204 Transactions. — Geology. 



crust of the earth where the great sea-beds join the continents. 

 But I do not see how this weakness could extend right across 

 the arch in the crust of the earth under the great sea-beds 

 from 40° S. latitude to 50° N. latitude, yet it is known that 

 the great earthquake of Lisbon in 1755 did shake such an arch 

 of the earth's crust over an area of 700,000 miles. 



This, however, is a question to be hereafter considered. 

 My present task is to set down the actual faces as I find them 

 in the Pacific. I have thought it right to add to the two lines 

 of volcanic action I first purposed pointing out the line of 

 upheaval along the 20th parallel of south latitude, from the 

 Loyalty Islands to the Cook Group, as well as the other facts 

 collected. I have not seen them specially referred to by any 

 other observer before. Huge active volcanoes exist in Central 

 America, the Sandwich Islands, Vulcan Island, and New 

 Guinea. With Mount Hecla near the North Pole, and 

 Mounts Erebus and Terror (and other active volcanoes in 

 Graham Land) near the South Pole, the Pacific volcanoes, 

 with Vesuvius and Etna in the Mediterranean, are nearlv the 

 only great safety-valves the planet now possesses. Evidences 

 of extinct volcanoes are abundant, but these are now far 

 removed from sea- water. 



The matter has its practical side, too, seeing that the 

 market need never be short of sulphur whilst there are such 

 great deposits of that mineral in Tanna or Ambrym in the 

 New Hebrides, or at the Mother and Two Daughters in New 

 Ireland, &c. The cultivators of the grape-vine in Australia 

 use hundreds of tons of sulphur. They will find plenty in the 

 different spots I have named. 



Our own White Island, off Poverty Bay, is still in a state 

 of volcanic activity, and must be regarded as the summit of a 

 crater but little elevated above the sea. It emits from time to 

 time volumes of white smoke. It produces, as I have said, a 

 great quantity of sulphur. Several cargoes have been sent to 

 Europe, and realised £8 a ton. It is very pure, containing 

 90 per cent. 



The intermittent action of volcanic energy referred to is 

 noticed in nearly all active volcanoes and geysers. It is very 

 marked at Tanna, and in some of our New Zealand geyser- 

 fountains the discharge is very regular as to time. There is, 

 indeed, one geyser in our hot-lake district so regular in its 

 discharge that I think it is called the " twelve-minute geyser " 

 (eight to ten minutes at Tanna, and ten to fifteen minutes at 

 Ambrym). 



The crater at Cotopaxi is situated in latitude 0° 41' S. and 

 longitude 78° 42' W., at a height of 19,493 ft. above the pre- 

 sent level of the Pacific Ocean, showing that once a safety- 

 valve is formed the internal fires keep as much as possible to 



