CHAPTER III. 



HISTORY OF THE SURVEY COIltimied. 



E now reach an epoch in the history of our explorations when it 

 may be more profitable to treat of the subjects of research each 

 by itself, than to speak of the yearly progress in each. The time had 

 arrived when we began to understand the structure of the White Moun- 

 tains, which knowledge proved to be the key to that of the rest of the 

 state. The field had been assigned to Mr. Vose originally ; but his resig- 

 nation left the place vacant, and it became the duty of the state geologist 

 to explore the territory in person. The special plan pursued in 1870 

 may be thus described. 



This laborious field of research includes particularly the region about 

 thirty miles long and twelve or fifteen wide, bounded by Israel's, Moose, 

 Peabody, Ellis, and Saco rivers. This area is nearly an unbroken forest, 

 traversed only by the bridle-paths and roads required for the ascent of 

 Mt. Washington by summer visitors. The plan pursued was, to visit sys- 

 tematically every one of the numerous peaks and valleys composing this 

 area with the hammer and barometer. As the first result of our labors 

 in the district specified, a physical model of the mountainous region was 

 constructed, about five feet in length, on the scale of one hundred and 

 forty rods to the inch horizontally, and one thousand feet to three fourths 

 of -an inch vertically. Contour lines were drawn for each five hundred 

 feet, and were made the basis for fashioning the mountains. With our 



