OF THE HAWAIIAN ISLANDS. 467 



northern pools has been noted on the plan. As the author was unassisted, save by a few kanakas who knew nothing 

 whatever of surveying, he was unable to make the numerous measurements necessary to the construction of a relief 

 model, but so far as the plan goes it is believed to be accurate. 



The sketch of the Exploring Expedition Survey shows the Black Ledge, and with the plan by Lieutenant Maiden, 

 who accompanied Lord Byron in 1825, will indicate the constant changes taking place in the topography of Kilauea. 

 Neither of these plans, however, were measured with sufficient detail to serve as standards of comparison except in 

 a general way. 



The explanation of the numerals on Lieutenant Maiden's plan, is as follows : — 



1. Crater in action visited by Lord Byron. 



2. Sulphur crater. 



3. Crater that broke out on the 29th of June. 



4. A cone very active all the night of the 29th. 



5. Largest crater, always emitting fire and smoke. 



6. Deep fissure in the lava. 



7. From this point it was 932 feet to the Black Ledge. 



8. Black Ledge 400 feet from the bottom of the crater. 



9. Lord Byron's encampment. 



10. A deep wooded crater. 



11. Steam cracks. 



12. A descent of twenty feet. 



On the northern bank there was a constant smoke from the sulphur banks, and the western end of the crater 

 was quite hidden by the thick vapors. Poli-o-Keawe was " thickly covered with green underwood ; " the descent 

 on to the neck between this and Kilauea was one hundred and fifty feet. 



In 1846 a sketch map was made of Kilauea, and on this the Black Ledge was estimated at G50 feet below the 

 highest bank. The whole interior was elevated from one hundred to one hundred and fifty feet above the Black 

 Ledge ; rough and broken, sloping towards the north. Halemaumau was some twenty feet above this plain. The lava 

 cataract of 1832 was estimated at three hundred feet in height. The walls of Poli-o-Keawe were four to five hundred 

 feet in height, and at the bottom was once a lake of lava thirty to fifty feet deep. Now the crust has fallen in and 

 is marked with tree holes ; it was from the outbreak of 1832. The variation near the house was 8° W. Steam 

 issued from the south-west bank near the spot marked on the large plan " Beds of Basaltic Pumice." 



Levelling revealed the curious fact that the surface of the various pools of melted lava was of different heights. 

 Halemaumau presented a surface sixty feet above the Lakes of 1864, and fifty feet above those of 1865. Even the 

 two pools of 1864 were not at the same level, but two or three feet different. With the great pressure lava must exert, 

 and the apparently free communication between the several vents, it is difficult to understand this, unless the viscidity 

 of the lava is greater at a considerable depth than on the surface. All the pools are above the base of the outer 

 walls. 



EXPLANATION OF THE WOODCUTS. 



[From Drawings and Photographs by the Author, unless otherwise specified. Engraved on 



wood by R. B. Dyer, except numbers 37 and 38.] 



Page 

 Fig. 1. Plan of the Koloa Craters (after Dana) ........... 346 



" 2. Cliff in Hanapepe Valley 349 



" 3. Natural Section in Hanapepe" Valley, a, a, prismatic basalt ; b, b, blue stone with concentric coat- 

 ing much fractured ; c, solid amorphous uucleus ......... 349 



" 4. View of Niihau from Waimea, Kauai. On the left is Kaula, on the opposite side Lehiia . . . 350 



" 5. Eastern end of Oahu. From the. north, distant fifteen miles ....... 353 



" 6. Map of the Valleys near Honolulu. A, small cone in Nuuanu ; B, circus of Nuuanu Valley ; 

 C, smooth conical peak ; D, Man6a Valley ; E, stream from Pau6a Valley ; F, stream from 



Makiki Valley 354, 436 



" 7. Side Ridge in Manoa Valley 355 



" 8. Cracks in the Manoa Ridge ............. 355 



