18 



MAGNETICAL OBSERVATIONS. 



OBSERVATIONS AT ORIZABA. 



Description of Station No. III. The instruments were mounted under a roof 

 of palm leaves, in the garden of MR. THOMAS GRANDISON, at Cocolapam, about a 

 thousand yards to the south of the town of Orizaba. A few hundred yards west 

 of the magnetic station rises a huge mountain ridge, of ancient volcanic rock, to 

 a height of 1,500 to 2,000 feet above the plain. This may possibly cause some 

 small local disturbance. 



The elevation of the station above the level of the sea was found by barometrical 

 observations 4,042 English feet. 



In the determination of absolute declination a break in a distant mountain ridge 

 to the eastward was used as a mark (A). 



No experiments of deflection have been made at Orizaba. 



STATION No. III. COCOLAPAM NEAR ORIZABA. 

 Latitude 18 53 . Longitude 97 V W. of Greenwich. 



