F. S. Dodge — Kilauea in August, 1892. 241 



Aet. XXIX. — Kilauea in August, 1892; by Feank S. 

 Dodge, Assistant Hawaiian Gov't Survey. 



By direction of Prof. W. D. Alexander, Surgeon General, 

 the writer was sent to Kilauea in August, 1892, to make such 

 surveys as were necessary to determine the change that had 

 taken place since the last survey in 1888. 



While it is unfortunate for the history of Kilauea in recent 

 years that no instrumental survey was made immediately after 

 the great break-down of March, 1891, we have estimates by 

 careful observers of the pit at that time, which range from 

 450 to 500 feet below the edge, or 750 to 800 below the Vol- 

 cano House datum, as compared with 900 feet after the col- 

 lapse of March, 1886. In this article, and the accompanying 

 plans and sections, all elevations are referred to the same 

 datum, as in my survey of 1886, viz., the veranda floor of the 

 old Yolcano House, which is approximately 4040 feet above 

 sea-level. 



Arriving at the volcano on the 18th of August, we began 

 the survey on the morning of the 19th, several points on the 

 main floor of Kilauea being located by triangulation, and their 

 heights obtained. The summit of the present floor is no 

 longer at "Central Rock" as in 1886, and 1888, but is now 

 about one-fourth of a mile to the westward, and sixty feet 

 higher, the great cone having built up by extensive overflows 

 from Haulema'uma'u, between July 1888, and March, 1891. 

 Careful observations from well-determined points show that 

 Central Rock has not changed its position, and it thus forms 

 a good point of reference for the survey of 1888, and that 

 recently made. 



From triangulation, with " Uckahuna " and V. H. A as a 

 base, four points on the edge of Halema'uma'u were accurately 

 located and their elevations determined, and from these points 

 the whole periphery was surveyed by stadia measurements. 

 From these same points, a large number of sights were taken 

 on small flags on the very rim of the burning lake, to closely 

 fix its exact size, shape and elevation, and the results are all 

 given on the maps. 



This survey gives the total area of Halema'uma'u as 100*4 

 acres, and that of the active lake as 12 1 acres, or equal to 

 that of a circle with a diameter of 820 feet, which is much 

 larger than any lake in Kilauea in recent years. Dana Lake 

 in 1888 was not more than 300 feet in diameter or l - 6 acres in 

 area. The present lake is nearly circular in form, its longest 

 diameter being 860 feet, and the shortest 800 feet. The 



