A Dome OH Halcmauman. 6i 



That there is a daily change of level in the dome-like floor of Kilanea, I cannot 

 doubt. The black surface absorbs the heat of the sun to such a degree as at times to 

 become unbearable to the touch. The casual visitor supposes this terrestrial heat, 

 when it is really solar. The nights here are usually quite cold, and the change from 

 midnight to noon must result in considerable expansion and contraction. In the early 

 morning I have repeatedly heard the tinkling noise caused by the sun's rays on the 

 cold lava as \\\&y displace the shadows of the cliffs ; and I once measured the change 

 in width of the great crack at the base of the dome on the trail across the crater, at 

 eight inches between early morning and noon on a bright day. If we had a suitable 

 observatory at Kilauea observations could easily be made all over the floor, and on 

 the surface of Halemaumau as well for change of level. 



But Mr. L^'man's visits, for he was again at Kilauea in August, were full of 

 information. He saw a thick cone, marked "furnace" on his plan, in full blast on his 

 second visit. Such a furnace as the writer saw in the summer of 1889. Lyman took 

 a few compass bearings in the crater, and with an improvised quadrant obtained the 

 height of walls. The Great Lake ( Halemaumau) he made twentj'-four hundred by two 

 thousand feet, and the surface ten or fifteen feet below his standpoint on the rim. The 

 lavas had an apparent motion to the southwest. 



1847 Halemaumau was, according to Mr. Coan, much in the same condition as 

 the previous j-ear.'"' 



1848 The lake was early in the year inactive, and the crust hardened and gradually 

 assumed a convex form. Dana states that soon after this swelling crust two 



thousand feet in diameter, was raised into a dome two or three hundred feet high, 

 covering the whole lake. Mr. Coan, from whom this information was obtained, adds 

 that in August the dome was raised almost high enough to overtop the lower part of 

 the outer wall of Kilauea and look out upon the surrounding country. From open- 

 ings in the dome the molten lava could be seen, and occasionally- sluggish lava rolled 

 in heav}^ and irregular streams down the sides. The dome as it now stands has been 

 formed by the compound action of upheaving forces from beneath and of eruptions 

 from the openings forming successive layers upon its external surface. Most of this 

 year no fires were to be seen even at night in Lua Pele. 



This is the first appearance of a dome in the history of Kilauea, and it is hard 

 to accept the elevation theory applied to a dome of the brittle nature of crust lava, 

 cracked and fissured in everj- part, with such a vast diameter, holding together for any 

 length of time even if its foundations were more solid than the brink of Halemaumau 

 affords at its best. To suppose this raised two or three hundred feet without interior 



"Amer. Journ. Science, 1851, xii, 80. [4391 



