J. D. Dana — History of the Changes in Kilauea. 23 



The conclusion arrived at while on the ground in August 

 last, was that Drayton's sketch represented sufficiently well the 

 existing outline of that part of the crater, that is, of the crater 

 of to-day. It follows, consequently, that the west wall of 1841 

 and of 1887 are essentially alike in position, and that Wilkes's 

 map of the southern half of its western wall is 1200 to 1500 

 feet out of the way. 



To make this large correction on Wilkes's map involves 

 some other large changes ; namely, the widening greatly of the 

 black ledge west of Halema'uma'u ; and also a probable widen- 

 ing of the Halema'uma'u part of the lower pit with the entrance- 

 way to it. Both changes are favored or required by Drayton's. 

 sketch. The entrance-way referred to is thus widened (on the 

 ground of Drayton's sketch chiefly), from Wilkes's 800 feet at 

 top of wall to about 1500 feet. The dotted line 1/1/1/ on 

 Plate 1 is believed to show the probable limit of the 1840 black 

 ledge along the west border of Halema'uma'u.* 



So large an error in so small a map excites an uncomfortable 

 query as to all the rest of its details ; fortunately not, however, 

 as to the depth of the crater and its lower pit, since this was 

 obtained by the independent measurements of two of the Expe- 

 dition officers, Lieutenants Budd and Eld. Moreover the map 

 may be used for some general conclusions. 



Drayton's sketch was probably taken from the point marked 

 Dn on the map, south of Wilkes's encampment, or on the higher 

 land to the west of this point. f 



The sketch has three headlands along the west wall. Of these, 

 only the second and third exist as they then were. The first or 

 nearest stood, as the sketch shows, between the Uwekahnna sum- 

 mit and the second of the deep western bays on Wilkes's map of 

 the lower pit, a spot where great subsidence has taken place in the 

 western wall, east or southeast of the Uwekahuna station (xxxiv, 

 358) ; and the sketch appears to be sufficient testimony for the 

 reality of this subsidence and its amount. 



Looking again at Wilkes's map (page 20), it is seen that, as al- 

 ready stated, the outer eastern wall has the same position that it has 

 on the Government map, but that the southeastern wall of Wilkes 

 is not continuous with his western, but is an independent one 

 situated more to the eastward ; and here came in the error. The 

 error is so extraordinarily great that we sought while at the cra- 

 ter for some extraordinary excuse for it. We concluded (Mr. 



* Another smaller change is proposed in the eastern outline of the lower pit, 

 near e, suggested by Brigham's map. No attempt is made to give on the Govern- 

 ment map Wilkes's outline of the southeast angle of the crater, as the existing 

 features offer no available suggestions. 



f While the sketch bears evidence of being generally faithful to the facts, the 

 foreground appears to be modified for the artistic purpose of giving distance to the 

 rest. 



