THE VISIT OF CAPTAIN WILKES.
Captain Wilkes of the United States Exploring Expedition made a prolonged stay at the two volcanoes in 1840-I, of which a full account is presented in the "Narrative," pp. 111-231. The part relating to Mauna Loa is given elsewhere. With this greater mountain in sight, Wilkes was quite disappointed when called to look at the uncouth black pits beneath his feet known as Kilauea. It was nothing but a depression, insignificant in comparison with the great plains and mountain, and exhibited scanty signs of fire. There was, however, a small cherry-red spot in the distance, above which was a cloud of silvery brightness. The depression itself, when properly examined, proved to be of grand proportions, three and a half miles long ,two and a half wide and nearly a thousand feet deep ; and he says the city of New York might easily be placed within it and have room to spare. At night the immense pool of cherry-red lava in a state of violent ebullition illuminates the whole expanse, flowing in all directions. With him were over two hundred native Hawaiians crowded upon the brink, gazing upon the scene in terror, fearing the vengeance of Pele for tres passing upon her domain.
The descent into the pit was by the route used at the present day, starting at the Volcano House. First was the descent of six hundred and fifty feet to the platform known as the black ledge. Continuing upon this shelf for a mile, he stood directly over the lake of fire, three hundred and fifty feet below, 1,500 feet long and i,000 feet wide. There was very little noise, and that was a low murmuring such as is heard in the boiling of a thick liquid. Oc casionally masses of red-hot matter were ejected to the height of about seventy feet ; then falling back. The lake was apparently rising, needing only a few feet of overflowing its banks.
The sketch made with the camera lucida by Mr. Drayton is re produced, Plate 28, and is one of the best ever made of the vol cano. It was taken from the north end. The lake of fire, which we know as Halemaumau, is in the distance. The vapors nearer arise from cracks in the lava, and consist of steam and sulphur ous gases. The platform which seems perfectly level is the black ledge, which before the late eruption is supposed to have extended entirely across the lower pit. The shelf is from six hundred to 2,000 feet in width, seamed by crevices. It is not so smooth as it would appear, as it is covered by large pieces of lava, and in places rises into cones thirty or forty feet high. Here and there are huge tortuous masses stretched lengthwise like hideous fiery serpents with black vitreous scales.
The lower platform is like the upper in most respects. It may be covered by a scoriaceous vitreous layer, which crumbles and cracks under the feet. Small patches break like glass. The un derlying basalt is firm and solid. A third variety is a black pumice. There are beneath, also, dark pits and vaulted caverns emitting blasts of heated air at the temperature of 18o°. The floor is three hundred and eighty-four feet below the upper plat form.
The lake because of its intense heat could not be approached nearer than 1,800-2,00o feet. It was discharging liquid matter
at short intervals directly across the most convenient route of travel. The capillary glass, known as Pele's hair, abounded in the crevices in loose tufts like tow ; and on the adjacent plain it adhered to bushes. These fibres may be straight with small drops of glass at one end, or crimped and frizzled, or may be spread over the ground like cobwebs.
On the return measurements were made and confirmed of all parts of the volcano, so that the data were obtained for a map and other illustrations. Dr. G. P. Judd, who had assisted very materially in managing the natives on the journey between Hilo and the summit of Mauna Loa, made the attempt to secure sam ples of the liquid lava. In pursuance of this quest he was gather ing specimens of the capillary glass on the steep wall of the smaller lake, having been let down by hand through the assistance of na tives. A slight movement in the lava arrested his attention. In a moment the crust was broken by a terrific heave and a jet of molten lava fifteen feet in diameter rose to the height of about forty-five feet with an appalling noise. In turning to escape he found himself under a projecting ledge and would have been over whelmed except for the friendly assistance of Kalumo, a native Hawaiian. Both were badly scorched by the heat. Wilkes called this pit Judd's Lake, found to be thirty-eight feet deep and two hundred feet in diameter. It was filled up in twelve minutes.
As an illustration of the variation of the conditions, upon the night following the narrow escape of Dr. Judd, the larger lake sank down one hundred feet, thus discharging a mass of melted rocks measuring fifteen million cubic feet. The lava ascends from unknown depths, pours over the borders of the lake, and then there may be a sudden falling away of the liquid because it has found a way of escape into some cavern or to the exterior of the mountain low down. These small escapades are the same in prin ciple with the larger infrequent so-called eruptions.
Plate 29 represents an attempt to delineate the interior of the volcano at the time of Wilkes' visit. The data employed are the original maps of the Exploring Expedition and the later Govern ment Surveys. Professor Dana has presented the details of the corrections needed by the Wilkes map which are all incorporated into this plate. It is assumed that there has not been a sufficient change in the position of the outer walls of the pit to show in a map of this scale. The black ledge and the pit are constantly changing. The special features of this map are the less depth of the walls back of the black ledge as compared with the early con ditions reported by Ellis and Malden, but a greater depth than has been visible since ; and the greater extent of the sulphur bank next to Keanakakoi. Wilkes' party encamped on the higher ground north of the volcano. The means are not in hand for a completely satisfactory representation of this "great lake" to which the name of Halemaumau belongs. This end of the lower pit is higher than the other.