PEEFACE BY THE EDITOR. Vll 



Besides the papers on Petrography, Paleontology, Botany, and Astron- 

 omy, it was Mr. Newton's purpose to include several chapters on the Dakota 

 Indians, and an account of the topographic work of the survey. The 

 former were prepared for his use, but have been reserved for a more appro- 

 priate place in the publications of the Bureau of Ethnology. The latter 

 does not appear among the papers. 



The topographic work was performed by the reconnaissance method. 

 The topographer traversed the district by numerous and intersecting routes, 

 sketching and observing the country as he went. His courses were esti- 

 mated by noting his traveling time. Their bearings and the bearings of 

 the features of the topography were observed with a prismatic compass. 

 Sextant observations for latitude were made by the astronomer each night 

 and at the midday camp. The whole was checked by a triangulation 

 including the principal peaks. There was no measured base line, but scale 

 was derived from the astronomical latitudes. The azimuth of the triangu- 

 lation was determined astronomically. Longitude was at first derived from 

 chronometers carried with the party, but a telegraphic determination, made 

 afterward, was adopted in the final map. 



Yielding to none in my appreciation of Newton's noble qualities and 

 brilliant promise, and sharing as geologist and friend in the regret and grief 

 at his untimely loss, I yet yield the place of biographer to his early 

 instructor and life-long friend, Dr. Newberry. 



Washington, D. C, May, 1880. 



