CONTENTS. 



PART I. MAGNETIC AL OBSERVATIONS. 



PAGE 



Instruments and methods of making the observations . 1 



Observations at Vera-Cruz 3 



Observations at Potrcro .... 12 



Observations at Orizaba . 18 



Observations at San Andres Chalchccomula . .22 



Observations at Mirador . 2G 



Observations at the city of Mexico 32 



Observations at Rancho Tlamacas ;;g 



Results of the magnetical observations . . 4o 



PAIIT II. NOTES ON THE VOLCANO POPOCATEPETL AND 



ITS VICINITY. 



General remarks . . .51 



llypsometrical determinations . . . 63 



Miscellaneous notes 83 



