CONTENTS 



Part I. — MAGNETICAL OBSERYATIONS. 



Instruments and methods of making the observations 



Observations at Vera-Cruz 



Observations at Potrero . 



Observations at Orizaba . 



Observations at San Andres Chalchecomula 



Observations at Mirador . 



Observations at the city of Mexico 



Observations at Rancho Tlamacas 



Results of the maffuetical observations 



[•AGE 



1 

 3 



12 

 18 

 22 

 26 

 32 

 38 

 45 



Part II.— NOTES ON THE VOLCANO POPOCATEPETL AND 



ITS VICINITY. 



General remarks . . . . . . . • 



Hypsometrical determinations .....••• 



Miscellaneous notes ....■•••• 



51 

 63 

 83 



