some observations made with chronometers. 
S 6 7 
and all the reductions would have been nearly correct both 
in latitude and longitude. But instead of proceeding in this 
manner, it seems to have been the intention to determine, in- 
dependently of any hypothesis respecting the figure of the 
earth, from a line, the length of which was ascertained by 
geodetical measurement, the length of a degree perpendi- 
cular to the meridian, in the same latitude in which the length 
of the arcs of the meridian was known by the distance of the 
parallels of Greenwich and Paris ; an arc of the meridian, 
and one perpendicular to it, being sufficient to determine the 
dimensions of the terrestrial spheroid. The line chosen for 
this purpose is the distance between Dunnose and Beachey 
Head (DB) ; its length was ascertained in various ways, all 
of which gave results nearly approaching one another. As 
the inclinations of the meridians of Beachy Head and Dun- 
nose (to the line DB) had been observed, and the latitude of 
the two spots were supposed to be known, both places having 
been connected by the Survey with Greenwich ; it is clear, 
that in the spheroidical triangle. North Pole, Beachy Head, 
Dunnose (PBD), the two angles B and D, the sides (PB 
and PD) and besides the length of the line BD are known. 
By resolving the spheroidical triangle PBD, the angle P (dif- 
ference of longitude of B and D) is ascertained. From this 
and the line DB, the length of the degree perpendicular to 
the meridian in latitude 50° 41' nearly, the middle point be- 
tween Beachey Head and Dunnose is determined ; and thence 
a spheroid, with a compression is found, on which all the 
reductions have been founded. The latitude of Dunnose, de- 
termined by its distance from the parallel of Greenwich, is 
50° 37' 7".3, or diminished by i'.gg ( the correction of the lati- 
