208 C. Abbe on the Repsold Portable Circle. 
position could be made accurate to within one or two seconds of 
arc, the central points of reference being referred with much 
greater accuracy to each other and to a very few zero points, 
then would these relative positions, as derived from astronomical 
observations combined with an accurate knowledge of the fig- 
ure of that portion of the earth’s surface covered by these sta- 
tions, suffice as groundwork for supplying the present wants of 
geographers and topographers. Inspired by the magnitude of 
the work, and supported by an interested military government, 
Struve and Tenner, co-working with the Norwegian and Swedish 
governments, sender out the astronomical and geodetical work 
recorded in the “ Are du Méridien de 25° 20’ entre le Danu 
with the surveys now being earried on by the British govern- 
ment, furnish the necessary determination of the figure of the 
San Francisco. to the present decade it must be conceded 
that the attention of geodesists has been perhaps too exclusively 
directe e measurements of degrees of latitude; it 18 now 
Mexico with the Pacifie eoast, taking advantage of the labors 
performed by the Mexican Boundary Survey we may be led to 
an arc of 33° on the parallel of 31° north, and the continuation 
