262 PROCEEDINGS OF THE ACADEMY OF [1890. 



I was not, however, able to determine this, as the lateness of the 

 hour prevented our reaching the position in question. Humboldt's 

 barometric measurement of the Pico del Fraile gave 462 J metres^ 

 or 15,161 feet; deducting the excess of 123 feet from his determina- 

 tion of the elevation of the City of Mexico we obtain 15,038 feet, or 

 about 80 feet more than my own calculations show. Garcia Cubas 

 reduces this difference by some 18 feet, giving as the height of the 

 mountain 4578 metres (15,020 feet).' 



Tabulating the results of our measurement of the four highest 

 volcanoes we find for : 



Peak of Orizaba 18,205 feet. 



Popocatepetl 17,523 feet. 



Ixtaccihuatl 16,960 feet. 



Nevado de Toluca 14,954 feet. 



Some slight alteration of these values, due to the effects of a vary- 

 ing temperature upon the mechanism of the aneroid, ought perhaps 

 to be made; but the correction is an unknown quantity, and I have 

 found that a change of from 20 to 30 degrees F. failed to produce 

 any appreciable difference in the reading. 



The Culminating Point of the North American 

 Continent. 



The restoration of the Peak of Orizaba to the first place among 

 Mexican mountains, and its increased altitude, open up the interest- 

 ing question as to what constitutes the culminating point of the 

 North American continent. The only other mountain that need be 

 considered in this connection is St. Elias, situated approximately 

 on the 141st parallel of W. longitude, and whose summit, is 

 claimed for both the possessions of Great Britian and the United 

 States (Alaska). The measurements of this mountain depart so 

 widely from one another, how^ever, that we are not yet in a position 

 to affirm, even within limits of 1000 feet or considerably more, how 

 nearly it approaches in height the Mexican volcanoes. We are 

 probably justified in dismissing without further examination the 



1 Essai Politique Nouv. Espagne, XCI ; 15,168 feet, in Cosmos, V, p. 281, 

 Bohn's Edition. 



2 I was informed in the town of San Juan that a number of students from the 

 engineer's college of Toluca determined trigonometrically the lieight of the Nevado 

 to be 4444 metres or 14,580 feet. I feel certain that this estimate is several 

 hundred feet too low. 



