ALTITUDES. 



253 



gave an unbroken series, wholly from levelling specially for this survey 

 along the entire course of the Connecticut river in New Hampshire. 

 Summary of the work connected with this series is as follows : 



Difference. Altitude. 



South Ashburnham Junction 1014 00 



Keene —535.42 478.58 



Bellows Falls —174.00 304.58 



South Vernon Junction 261.36 



Brattleborough —32.95 228.41 



Bellows Falls +76.17 304.58 



Charlestown, -|-70.88 375.46 



Claremont Junction, +98.05 473.51 



Windsor . —142.31 331.20 



White River Junction, +38.03 369.23 



The altitudes comprised in these two reference lines are arranged in 

 full under Nos. i, 2, and 3 in the tables of this chapter. The last of these 

 contains the heights determined along Connecticut river, the reliability of 

 which is attested by the close agreement of four series directly from the 

 sea, viz., through South Ashburnham, through Concord, and by way of 

 the Portland & Ogdensburg Railroad and the Grand Trunk Railway. 



From Boston, by way of Boston & Maine, Portsmouth, Great Falls 

 & Conway, and Portland & Ogdensburg Railroads, to Dalton. 



A third reference line, extending along the eastern portion of the state, 

 and connecting with the Connecticut river series at Dalton, has been 

 obtained entirely from railroad surveys. These altitudes from Boston to 

 Great Falls were taken from the original profile of the Boston & Maine 

 Railroad, through the kindness of Pres. White, at his office in Boston. 

 On this profile, reference was to marsh level (high tide), and S feet have 

 been added to the figures there given for height above mean tide. 

 These figures show an exact agreement at Newmarket Junction with the 

 series measured by the Messrs. Woodbridge, and again at Great Falls 

 with the altitudes furnished by T. Willis Pratt, engineer of the Ports- 

 mouth, Great Falls & Conway Railroad, from mean tide at Portsmouth. 

 By this latter series the line is continued to North Conway. The levels 

 for the Wolfeborough Branch, including the altitude of Lake Winnipiseo- 

 gee, were furnished by George L. Whitehouse, Esq., of Farmington, and 



