256 



PROCEEDINGS OF THE ACADEMY OF 



[1890. 



Correction for latitude (deer, grav.) 

 Correction for gravity (vertical) . 

 Correction for elevation of lower station 



Elevation of Mexican Observatory 



Tables of Guyot : 



Difference of barometric values 

 Addition for temperature 

 Correction for latitude 

 Correction for gravity 

 Correction for lower station 



Elevation of Mexican Observatory 



Computed from the readings at Vera Cruz 

 Tables of Guyot : 



Difference of barometric values 



Addition for temperature 



Correction for latitude 



Correction for gravity 



Correction for lower station 



17,533.6 feet. 

 It is not necessary in this place to recite all the previous measure- 

 ments of Popocatepetl that have been made, which in a general Avay 

 agree in giving the mountain an elevation of from 17,400 to 18,000 

 feet. The brothers Glennie reached the highest point of the crater- 

 wall on the 20th of April, 1827, and by bai'ometrical observations 

 deduced its height to be 17,884 feet.^ The opposite to the extreme 



1 Humboldt (Cosmos, V, p. 458 Bohn's Edition) states that this measurement 

 had been corrected by Burkart into 18,017 feet. 1 find no reference to this correc- 

 tion in Burkart's original communication (translation of Glennie's narrative) 

 published in Schweigger's Jahrbuch der Chemie und Physik, XX, pp. 385 etseq. , 

 1827. Glennie, however, gives the pressure of the barometer as 15,63 inches, 

 which, if taken under conditions similiar to those which marked our own measure- 

 ments, would indicate a value of upward of 18,000 feet. But no statement is made 

 as to the testing of the barometer for accuracy. 



