22 J. D. Dana — History of the Changes in Kilauea. 



some reason it requires the same correction. Such a discrep- 

 ancy unavoidably throws doubts over other parts of the maps. 

 But while closer study increases confidence in Mr. Brigham's, 

 the result is not so satisfactory with the Wilkes map. The 

 following remarks suppose the scale of the two maps to have 

 been corrected. 



Wilkes's map of Kilauea. — The relations of the map made 

 by Capt. "Wilkes to that of the Government Survey is exhib- 

 ited on Plate 1, the outline of the crater from the former being 

 drawn over the latter where it is essentially divergent. This 

 diverging part of the outline is lettered ABCDE,DE show- 

 ing the outline of the sulphur banks of 1840. Besides this, 

 the outline of the black ledge of 1840 is indicated by the line 

 L L L, and its surface by cross-lining. Some important features 

 from Brigham's map also are drawn in and indicated by italic 

 letters. These include small lava-lakes, the outline of Hale- 

 ma'uma'u as given by him, small cones, fissures, etc. 



The plate shows, in the first place, a general conformity be- 

 tween the eastern wall of the Wilkes and Government maps, 

 but a far greater width of sulphur banks in that of 1840. 

 These sulphur banks have become submerged by the lava flows 

 of later time, and thus the floor of the crater has in this part 

 been extended eastward about 2500 feet. Of this I believe 

 there is no doubt. 



In the second place, there is no conformity between the 

 maps in the southern half of the western wall. Instead, on 

 Wilkes's map, south of the Uwekahuna station, the west wall 

 (ABC on Plate 1) is 1200 to 1500 feet inside of the position 

 of the existing wall as given on the Government map ; show- 

 ing, apparently, a very great topographical change on that 

 side of Kilauea since January, 1841, and one of the highest in- 

 terest ; a change either by subsidence, or by overflowings of 

 lava streams, adding nearly 10,000,000 square feet to the area 

 of the crater. 



Looking about for other evidence of this change, and finding 

 no allusion to it in Mr. Coan's reports, and nothing in Mr. 

 Lyman's paper or map of 1846 (xxxiv, 83), but, on the contrary, 

 a general conformity in Lyman's map to that of the recent 

 survey, I was led to question the unavoidable conclusion, 

 although it involved a doubt of the Wilkes map. A conse- 

 quence of the doubt was my sudden determination to revisit 

 Hawaii and sustain the conclusions from Wilkes's map if possi- 

 ble ; for they made too large a piece in the history to be left in 

 doubt. Mr. Drayton's sketch, reproduced as Plate 12 in a 

 former part of this paper (xxxiii, 437), suggested the method 

 of deciding the question. 



