466 W. T. BRIG HAM ON THE VOLCANIC PHENOMENA 



EXPLANATION OF THE PLATES. 

 Plate XI. Kauai, Niihau. Kaula, and Lehua. 



This Map has been constructed from several manuscript maps kindly furnished by residents. As no general 

 survey has ever been made, either of Kauai or any other island in the group, it is not as accurate as could be desired, 

 but is believed to be an improvement upon any yet published. The island of Niihau has been surveyed by Mr. G. 

 N. Wilcox of Kauai. 



Plate XII. Oahu and the Hawaiian Group. 



The Map of Oahu is drawn mainly from that given by Prof. Dana in the " Geology of the Exploring Expedition." 

 The exact position of many of the valleys is as yet undetermined, and it has been necessary to merely indicate their 

 general form and relation to each other. For the same reason the dotted line which represents the fringing reef 

 denotes the position and general extent rather than the exact topography of the coral formation. 



The Map of the whole group shows both the relative position of the various islands and action of the volcanic 

 vents. Where these have clustered around a single point, as on Hawaii and Maui, a circle represents the position; 

 where the line of eruption is elongated, as on Oahu, an elliptical figure is used for the same purpose. The radiating 

 lines serve to connect with these centres the various lateral cones which stud the great domes in determinate lines to 

 the very shores, or even extend into the sea, as in the crater of Molokiui. So far as is known, all the lateral cones 

 •will fall into the lines represented, and it will be seen at once that they are remarkably parallel to four directing lines. 

 The centre on the western part of Kauai has been divided, to show the relation of Niihau as previously suggested. 

 The same has been done with Lanai and Kahoolawe, although this is perhaps unwarranted. 



Plate XIII. The Maui Group. 



West Maui has been drawn chiefly from a manuscript Map by Mr. Horace Mann, and represents fairly the relative 

 positions of the valleys. 



Plate XIV. Hawaii. 



One of the original features of this Map is the lava flows. Those along the coast have been represented from 

 actual observation, and are only those whose aspect is still perfectly fresh and distinct; farther up the slope they are 

 lost in the dense forest, and although they proceed from near the summit in almost every case, their upper course has 

 never been traced. Mauna Kohala has been represented nearly in its true position, and Kilauea has been recognized 

 as an independent mountain. The region in the district of Hilo south of Laupahoehoe is not represented in its true 

 character, as it would be difficult to even indicate on so small a scale the extraordinary nature of the intersecting 

 ravines. The streams show the position of the largest, but as there are more than fifty large streams in a distance 

 of thirty miles less than half are shown. 



Plate XV. The Crater of Kilauea. 



This plan lias been constructed from a careful survey by the author. Starting from the house at the north-east 

 bank the circumference was chained, making the distance between the twenty stations on the wall of the crater 

 8.6865 miles. From each station bearings were taken with a large theodolite made expressly for the purpose. 

 The summit of the Cathedral in the crater was made a central point to determine the relative height of the banks. 

 The side crater, Poli-o-Keawe. was not measured. Many of the cracks in the walls of the principal crater are not 

 figured, and other details are omitted. A section across the southern end from A to B will give a fair idea of the 

 elevation of the bottom towards the centre. 



At each station the magnetic meridian was compared with the true meridian, obtained by careful observations 01 

 the pole star at its ea<t and west elongation and the remarkable variation observed in the neighborhood of the 



