450 J. D. Dana—History of the Changes in Kilauea. 
the discharge of lavas and a consequent down-plunge in the 
crater, there was again a lower pit with a black ledge. He 
gathered facts showing that the eruption began on the 30th of 
May, made itself apparent at intervals down the eastern slopes 
of the mountain, finally broke out as a stream twelve miles 
from the coast and flowed into the sea just south of Nanawale; 
and that the flowing continued for three weeks. The condi- 
tion of the crater in November, the time of my visit, agrees 
well with the view in the accompanying Plate (PJ. XII) which 
was taken two months later. The route to the seashore was 
surveyed by the officers of the Expedition in January, and less 
perfectly by myself in November. 
My failure to survey the whole route of the lavas to the sea- 
coast and investigate other parts of Hawaii was in obedience to 
orders. The vessel of the Expedition to which I was attached— 
the sloop-of-war ‘“‘ Peacock ”—was at the time already under sail- 
ing orders for hydrographic work in the equatorial regions of the 
Pacific; and, although the geologist of the Expedition, I was 
required to go off with her, away from the most important field 
of geological investigation in the ocean. Only a week was 
allowed me for Hawaii. I left the region of volcanoes with 
a silent protest—the only safe kind—but found compensation 
through work in another field ; and though an old field to me, it 
was one of unexhausted delight and instruction—the coral islands 
of the central Pacific. I was enabled to add much to the knowledge 
of reefs, corals and crustaceans which I had gathered during the 
preceding season in the Paumotu, Society, Samoan, Friendly and 
Fejee Islands, by excursions and studies in the Union Group of 
atolls, the Phenix Group, the Kingsmill or Gilbert islands, and 
others. Captain Wilkes had once (while we were off Patagonia) 
sent me word, when I was seeking information from the log-book 
of his vessel as to the winds of a Cape Horn gale, that he had 
that department in charge. At the Hawaiian Islands it was made 
to appear that at his pleasure, he had the geological department 
also in charge, although he knew nothing of the subject. The 
“ Narrative,” however, was intended to include all departments ; 
and the energetic commander was never conscious of incapacity 
in any direction. ~ 
7. AFTER THE ERUPTION OF 1840.—sSize of the Crater.— 
Capt. Wilkes states, on page 123 of the 4th volume of the Nar- 
rative, that the “black ledge surrounds it [the crater] at the 
depth of 660 feet, and thence to the bottom is 384 feet ;” and 
four pages beyond: “the black ledge is of various widths, from 
600 to 2,000 feet.” The black ledge “‘ was found [to be] 660 
feet below the rim.” The floor of the crater ‘‘ was afterwards 
found to be 384 feet below the black ledge, making the whole 
depth 987 [1,044 ?] feet below the northern rim.” 
