20 J. D. Dana — History of the Changes in 7£ilauea. 



along the border of the crater; and (2) overflowings and changes 

 of level over the bottom. 



Down-falls of the walls and sinkings of the borders are re- 

 ported as having been common during periods of eruption and 

 earthquake ; but direct testimony as to the amount at any time 

 does not exist. In view of the great numbers of deep fis- 

 sures about Kilauea (xxxiv, 358) and the many fault-planes and 

 sunken areas, the fact cannot be doubted ; and Mr. Brigham 

 has estimated" that the crater in 1880 was five per cent larger 

 than it was 18 years before. The increase in mean diameter 

 on this estimate would be 300 feet. I think the estimate large. 



KILAUEA 



U. S. EXPL. EXPED. 



Of the gradual changes over the bottom of the crater pretty 

 full records have been gathered from the published accounts. 

 But we naturally look with the greatest confidence to the maps 

 that give the results of personal surveys, especially with regard 

 to changes in the outline of the walls. We have two such 

 maps — that made personally by Wilkes in 1841, and that by 

 Brigham in 1865, besides the recent map by the Hawaiian 



*This Journal, III, xxxiv, 20. 



