April 29-30. A party of fourteen persons with two guides and three helpers, made the ascent while the conditions were in teresting. Mr. F. S. Dodge marked the peculiar features of the eruption upon a copy of the plan of Rev. Mr. Alexander. The new lava covered about half the area of the main pit. The foun tains of lava occupied the place where they have always been re ported; and there was a deep pit near the south wall. They did not descend to the lower levels.
In 1906 Mr. H. B. Guppy, an English Naturalist, published an account of a three weeks' sojourn upon the summit of Mokua weoweo, Aug. 8-13, 1897. The air was highly electrified. He could trace letters upon his red blanket at night in phosphorescent lines. The air was also very dry, leading to the following physiological effects ; cessation of the action of the skin, severe headaches, sore throat, tendency to palpitation, dyspncea, sleep lessness, lassitude and loss of appetite. Most of the unpleasant symptoms disappeared when damp weather intervened. Just be fore sunrise and after sunset the shadow of the mountain was thrown back against the sky. The range of temperature was twice as great as on the coast. He made many descents into the pit on the northwest side. In dry weather smoke issued from near the center of the pit and in the southwest corner, where are deposits of sulphur, and whence moist vapors arise from nearly the whole surface. These are white, and are supposed to be rising all the time, but are invisible except when there are clouds over head or it is damp. Very much vapor discharged from South Mokuaweoweo, which is the "smoke" sometimes observed from Kona. Insect life is abundant, having been brought up by a southerly wind.
Mr. Guppy made important observations upon the history of the caldera during his sojourn on the summit, which were pub lished in the Advertiser, September 6-8, 1906. The great an tiquity is proved by the slight differences of contour shown since 1840, as well as the depth—at first seven hundred and eighty-four and in 1885 eight hundred There have always existed the great central cavity, the north and south banks and the pit that has been termed South Mokuaweoweo. The small pit at the north end must have existed though it is improperly located. upon Wilkes' plan and is not specified upon Lydgate's sketch, but was spoken of by Dutton in 1882. The crater-producing pro cesses new operating in the caldera are the formation of lower pits either in the main cavity or the adjoining areas, the continual lateral enlargement of the principal depression by slips from the sides and the occurrence of two areas at the northeast and south west where there is a constant discharge of aqueous vapors. None of the pit-craters contain ejected materials heaped up at their borders, but Pohaku Hanalei, about a mile southwest of Mokuaweoweo, is formed of lava ejected in the molten state and loose blocks, making a cone two hundred feet high, and its base five hundred or six hundred feet below the caldera.
His views of the origin of the caldera are briefly summed up as follows : "It would seem that Mauna Loa has been raised over a deep-seated fissure running N.E. and S.W. for a distance of at least ten miles, and quite independent of the focus of Kilauea. This huge mountain presents in the great terminal basin of Mo kuaweoweo evidence of its own decay as a volcanic vent. After the coalescence of the line of pit craters on its summit, its condi tion was doubtless comparable to that of Kilauea in our own time. Then with the defervescence of its activity, the level at which the lava was maintained in a permanently liquid condition fell lower and lower until it lay as it does now, several thousands of feet below the summit. From time to time, however, there was recrudescence of volcanic heat resulting in the rise of the level of the permanently liquid lava towards the summit, the solid floods of the terminal craters reliquifying with the access of heat, whilst the crater walls were continually undermined by the partial remelting of their foundations. During the periods of quiescence the great basin grew in breadth by the rifting and falling in of its walls, and the products of its own decay were remelted as they lay on the floor during each recrudescence of activity. It is in this condition that Mokuaweoweo presents itself at the present day." In the study of the spring waters in the southern part of Hawaii Mr. Guppy finds facts that sustain the proposition that Mauna Loa and Kilauea are separate centers of influence. "As far as the temperatures of the underground waters can guide us, we are able to distinguish on the southeast coast of Hawaii between the respective zones of influence of Kilauea and Mauna Loa. The thermal regions of the two zones are sharply contrasted. Along the whole length of the south coast of Puna, beginning at the modern lava flow that reaches the coast at Keaiwa, about half way between Punaluu and Kapapala Bay, the underground waters of a greater or less degree display a temperature increased by the vicinity of volcanic action. This is the Kilauea zone of influ ence, and the excess of heat here acquired by the underground waters varied in amount from three to four degrees above the mean temperature of the air for January (seventy-two degrees) to as much as twenty-five. On the other hand, west of this zone in the Punaluu district we find cool perennial springs display ing a constant temperature at the coast all through the year of about 64 degrees ; whilst an inland spring at an elevation of 3,000 feet had a temperature of 58.5 degrees. This is the Mauna Loa zone of influence ; and we have here then an indication of the independence of the two zones so far as the temperature of the underground waters is concerned."