E. 8. Dana — Petrography of the Sandwich Islands. 457 



the shell should have formed first and that these tubes should 

 have lengthened by the material carried down within them, 

 finally resulting in their becoming solid to a greater or less extent. 

 This is confirmed by the fact that the parts seemingly most 

 solid often prove to have at the center 

 minute crystal-lined cavities. The lengthen- 

 ing by the addition of material at the point 

 of attachment above, the only other method 

 that can be suggested, is difficult to conceive 

 of. 



As the facts at hand are inconsistent with 

 the theory of a direct formation from the 



melted condition, we are forced to speculate 



. , <? .li i • i i i - j j. Transverse section 



as to the power of the highly heated water of lava sta iactite from 



vapor known to be present in large quantities, Kilauea ( x 2) show- 

 to form them from the roof by a sort of proc- mg first formed stalac- 

 ess of aqueo-fusion. This is a subject about 

 which we know too little at present to make speculation very 

 profitable, and the author prefers to drop the discussion here, 

 in the hope that further observations may throw important 

 light upon the matter. The experiments of Fouque and Levy 

 in regard to the formation of basalt, with their important re- 

 sults, pursued the method of simple igneous fusion, and though 

 Delesse and Daubree have discussed the role of water in the 

 formation of basalt and basaltic minerals, their investigations 

 hardly seem to apply very closely to the present case.* 



The fact that these stalactites occur also in the caverns of 

 Kilauea has already been mentioned. Brigham describes them 

 at some length, and although it is hardly possible to accept all 

 his statements literally, especially as to rate and conditions of 

 growth, his remarks are quoted here at length (1. c, pp. 462, 

 463): 



"A formation which always excites the curiosity of visitors to 

 Kilauea is found in many of the caves in the floor of the crater 

 which have been undisturbed for several years. At first glance 

 the tubes which hang from the roof and the curiously formed 

 droppings beneath these, seem to be of igneous origin. An ex- 

 amination in situ shows that this was not the case. The roof of 

 these caves is about two feet thick and generally unbroken ; the 

 stalactites do not occur under cracks and indeed there is often no 

 fresh lava over the surface. The formative process may be 

 clearly seen as the tubes form from day to day ; and I have 

 caught the steel-gray deposit in the drops on the end of the tubes 

 upon my finger and watched its solidification. Usually the tubes 

 are straight cylinders from one to three-eighths of an inch in 



* Meunier has described the formation of chrysolite and of chondrules of en- 

 statite, resembling those of meteorites, by the action of steam at ordinary pres- 

 sures, with silicon chloride upon the red hot metal, C. E., xciii, 737, 1881. 



