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



bad defining lines and imperfect focus, the wonder is that the 

 results are as good as they usually are. It is hard to say what 

 material is least liable to changes, but it is quite certain that 

 substances of crystalline structure, and alloys of which the phys- 

 ical properties are largely dependent on a nearly definite com- 

 position, should be avoided. Probably pure platinum, silver, 

 and copper, annealed with the utmost care, and kept for some 

 years before final graduation, are less likely to change than 

 any other material which we know. For short standards, possi- 

 bly bars of native copper, prepared with as few strains as pos- 

 sible, would give the closest possible approximation to a mate- 

 rial which has arrived at a permanent state. 



Physical Laboratory, Johns Hopkins University, Feb. 22, 1886. 

 [To be continued.] 



Akt. XXIII. — History of the changes in the Mt. Loa Craters', 

 by James D. Dana. Part I. Kilauea. Continuation of 

 the Summary and Conclusions. (With Plates IV and Y). 



[Continued from xxxiii, 433; xxxiv, 81, 349; xxxv, 15, 181, 1888.] 

 B. The Ascensive Action in the Conduit lavas. 



1. Evidence. — The evidence in favor of an uplifting action 

 by the ascensive force has been presented in volumes xxxiv, pp. 

 83, 89, and xxxv, p. 25. It is briefly as follows : 



(1) The observations in 1846 by Mr. Chester Lyman demon- 

 strate that in six years the lower pit of 1840, averaging 10,000 

 feet by 2,500 in its diameters and nearly 400 feet in depth, 

 had gradually become obliterated, and chiefly through an uplift 

 of the floor ; for the floor bore on its surface the talus of lava 

 blocks that, had fallen from the walls. Overflows had done 

 part of the work, but " subterranean force," as Mr. Lyman con- 

 cluded, the larger part. Mr. Coan, who was with Mr. Lyman 

 at the time, appreciated the evidence, and later described the 

 lifting as " not uniform in all parts ; as sometimes taking place 

 here and there abruptly ; but as producing nearly uniform re- 

 sults, except a greater rise toward Halema'uma'u.'' 



(2) In 1868, Mr. Brigham gave further evidence as to the 

 Lyman ridge by the representation of what remained of it in 

 1865 (xxxiv, 89, and xxxv, 24), on his valuable map, though 

 not, as his memoir shows, understanding its origin. Besides 

 this, the painting of the crater of about the same date (1864 or 

 earlier) by Mr. Perry afforded confirmatory proof as to its 

 position and extent at that time (xxxv, 25). 



(3) In 1848, Mr. Coan observed that a cone of broken lava 

 that had formed within the Halema'uma'u basin, was lifted by 

 " subterranean action," as he argued, because only slight addi- 



