PREFACE. 



It has been found impossible to treat of the subjects of metamorphism, 

 elevation of mountains, and earthquakes within the limits of this volume, 

 as originally contemplated, but we hope not to neglect them altogether, as 

 provision has been made for the printing of another book, devoted more 

 particularly to geology and mineralogy, in which these topics will be fully 

 discussed. 



Some of the following chapters have been prepared by gentlemen eminent 

 in their several specialties, not officially connected with the Survey, who 

 have kindly devoted their time and strength to the work without remunera- 

 tion for their services. To them our thanks are specially extended. 



Mr. Warren Upham, of Nashua, compiled the interesting chapter upon 

 the History of Explorations among the White Mountains, and the descrip- 

 tion of the river systems. If the observations upon altitudes constitute the 

 most thorough and perhaps most useful chapter in the volume, it is due to 

 the indefatigable diligence of Mr. Upham, in comparing the various railroad 

 surveys from different parts of the state, sifting out what seemed unreliable, 

 and matching them together into one connected whole. 



With such substantial foundations established for the elucidation of the 

 water-power of the state as are afforded by these two chapters, it is to be 

 hoped that the Executive will call to mind an act passed by the legislature 

 in reference to the appointment of a hydrographic commission. The infor- 

 mation in this report would be of so much service to that commission, that 

 the sum appropriated for their work would be sufficient to bring out results 

 of great benefit to the state, which could not otherwise have been obtained 

 to so good advantage. 



