12 



MAGNETICAL OBSERVATIONS. 



OBSERVATIONS AT POTRERO. 



Description of Station No. II. Potrero is the first large sugar estate on the 

 road from Vera Crux to Orizaba, about twenty miles to the east of the last-men 

 tioned town. Its elevation above the level of the Mexican Gulf was found 1,988 

 English feet (by barometrical observations). The magnetical observations have 

 been made in a shed or barn, consisting of a roof of palm leaves supported by a 

 number of poles. There is no iron within several hundred yards of it. The shed 

 is situated about eighty yards to the N. N. &quot;W&quot;. of the store. A tree, nearly four 

 miles to the west of the station, was used for a mark (A) in the determination of 

 the absolute declination. 



STATION No. II. I OTRERO. 

 Latitude 18 50 . Longitude 96 48 W. of Greenwich. 



