406 Wood — Effects in Jfokuaweoweo of the Eruption of 19 11^. 



of the summit point, are given out by the office of the 

 Territorial Survey as 



19° 28' 50-26" N. Lat. 



155° 36' 2766" W. Long, from Greenwich. 



The elevation of this station was found by triangulation as 

 13,650 feet (about 4,160 meters) above sea. 



Accepting these coordinates and this scale as accurate, the 

 meridians and parallels drawn on the maps, figs. 1 and 13, 

 have been plotted with care. However, they do not agree 

 with values determined by Wilkes in 1841, nor with those 

 determined by Green, in 1913, (working, only, to tenths of 

 minutes of arc). Andn one of these agrees with the coordinates 

 plotted on the cut of this map published by Brigham.* Pre- 

 sumably the Alexander values, stated to hundredths of seconds 

 of arc, are accurate — at any rate more so that the others. 

 But it is proper to bring to notice these discrepancies since 

 they cast doubt in some degree on the accuracj 7 of the carto- 

 graphic net. 



The 1885 map, fig. 1, is simply re-drawn, by tracing methods, 

 from a bine-print copy. Some changes in lettering have been 

 made and some new lettering added ; and certain things shown 

 on the copies published by Dana and Brigham, but not on the 

 blue-print copy, are here added. 



The revised map, fig. 13, makes no pretense to strict carto- 

 graphic accuracy. But an attempt has been made to express 

 upon it changes, which strike the attention of the observer, 

 that have taken place in the outline, and upon the floor, down 

 to August 1915. Unfortunately, this revision contains an error. 

 The line of new rift-cones drawn on it was fixed by a compass 

 triangulation, (a method obviously uncertain in an area of 

 rapidly varying magnetic variation, as is the case here) : after 

 the map was completed it developed from the critical study 

 and measurement of the photographs that this line, as drawn, 

 is slightly out in azimuth. Its northern end, E, should be 

 swung eastwardly about five degrees around its southern end, 

 F, as a center. 



No new surveying data, except with pocket compass, have 

 been obtained. However, the revised map has been made 

 with much care, — especially from the geologist's point of 

 view — , and the study and measurement of many photographs 

 is embodied in it, as well as the other results of the direct work 

 in the field. Except for the error mentioned it is thought to 

 be substantially accurate. This is true also of the cross section, 

 fig. 14. 



* W. T. Brigham, The Volcanoes of Kilauea and Mauna Loa, Mem. B. P. 

 Bishop Museum, IT, 4, p. 159, Honolulu. 



