12 



MAGNETICAL OBSERVATIONS. 



OBSERYATIOXS AT POTRERO. 



Description of Station No. II. — Potrero is the fir.st large sugar estate on the 

 road from Vera Cruz to Orizaba, about twenty miles to the east of the last-tnen- 

 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. W. of the store. A tree, nearly four 

 miles to the west of the station, was used for a mark {h.) in the determination of 

 the absolute declination. 



Station No. II. Potrero. 

 Latitude 18° 56'. Longitude 9G° 48' W. of Greenwich. 



