40 Some Account of the IVhtle Mountains 



com}5litat!on is founded, it may be observed, that the barometer 

 employed was of the most approved and modern construction, 

 being guarded against accidents with an express vievy to its use 

 in expeditions of this sort ; that it went and returned without 

 injury; and at the end of the journey agreed with other instru- 

 ments at the university, precisely as it had done before its re- 

 moval. 



In confirmation of the present estimate, it may also be ob- 

 served, that a geometrical admeasurement, taken by Dr. Shat- 

 tuck and others from the plain in front of Rosebrooks house, 

 gave to the summit an elevation of 4,620 feet above that place. 

 This being added to 1,(548, the barometrical height of Rose- 

 brooks above the sea, will give a total of 6,268 feet, differing 

 only forty-three feet from our estimate. 



W. Maclure, Esq. author of the geological map of the United 

 States, informs me, that from two geometrical admeasurements 

 made some years since on the eastern and western sides of the 

 mountain, he arrived at results nearly similar. 



Minerals. 



The White Mountains when viewed from the westward, present 

 a long ridge bounded by an undulating or serpentine line. On 

 a near view, the outline is found to be notched and ragged, but 

 wholly destitute of sharp cliffs and needles, or sudden perpendi- 

 cular eminences. When the mountain is ascended, its upper- 

 most or bald portion, 1,800 feet in height, is found to consist 

 wholly of a loose, irregular, disconnected heap of rocks, of all 

 shapes and dimensions, from one to thirty feet in diameter, lying 

 confusedly one above another, but all resting firmly in their 

 places, having found situations where they can resist the torrents, 

 that roll over them, in descending the sides of the mountain at 

 certain seasons of the year. These rocks are of gneiss and mi- 

 caceous schistus, or rather of an intermediate substance between 

 the two, approaching sometimes the one and sometimes the other. 

 The mica is abundant and brilliant, but its stratification is un- 

 even and irregular, and often interrupted by thin strata of 

 cjMartz. Owing to the irregular position of the rocks, their 

 strata are found resting in every possible direction. Large veins 

 of quartz very frequently traverse them, and specimens of pure 

 mica may occasionally be obtained, the plates of which are se-- 

 veral inches in diameter. There is nothing in the colour of the 

 rocks which can in any way account for the white appearance of 

 the mountains, since they are uniformly incrusted with dark -gray 

 lichens, which give them an almost blackish appearance. Their 

 distant white appearance can only be accounted for by the pre- 

 sence of snow, which covers the summits for two-thirds or more 



of 



