— 312 Annual Report on the U. S. Coast Survey. 
the New England coast. Observations have been assiduously 
continued at this place by Wm. Mitchell, Esq., and his assistant. 
His method of determining the longitude by chronometers 
tween Boston and Liverpool, has been continued by William C. 
Bond, and fifty-two results from twenty-three chronometers have 
been reported. 
The use of the new instruments has served to verify a remark- 
able conclusion arrived at in the observations of a former year. 
In places near each other, and where the plumb line cannot be 
influenced by the attraction of mountains, the latitudes derived 
from geodetical and astronomical data, do not agree with each 
other, or in other words, the difference of latitude of two places 
in the vicinity of each other, is not found the same when derived 
from the triangulation between the two places and from separate 
astronomical observations. The latitudes of New York and Bos- 
ton do not agree when compared by the two methods. Boston, 
Cape Henlopen and New York differ from Philadelphia ; and the 
various stations about the city of New York, when transferred to 
a central point, are all at variance with each other. This result, 
intimately connected with the questions of geology and the figure 
of the earth, was first announced in this Journal in 1845, and 
was referred by Dr. Bache to irregularities of gravitation occa- 
sioned by variations in the form and density of the material com- 
posing the crust of the earth. A discovery of the same kind has 
since been made by Major General Colby, in the ordnance survey 
lorchester or Cambridge during a period of twenty-seven years. 
Lieut. Gilliss has been engaged in the comparison of the long 
