33 2 Don J. Rodriguez’s Observations on the 
Now if we take the arithmetic mean of the sums contained 
in the two tables, we have for measures of the entire arc, 
comprised between the stations of Clifton and Dunnose, the 
following quantities 162057,32 toises, and 10221,972 seconds 
of a degree, or 2 0 50' 2i",972. By dividing the former of 
these by the second, we get the measure of a degree, corres- 
ponding to the mean latitude of the whole arc, equal to 
57073,74 toises, or 60826,34 fathoms, at the temperature of 
i6|° of the centigrade thermometer, the latitude being 52 0 
2' 20". 
The station at Arbury Hill happens to be very nearly in 
the meridian of Clifton and Dunnose, and divides the interval 
between them into nearly equal parts. The measures of that 
part of the arc, which lies between Arbury and Dunnose, is 
by the tables 91679,47 toises, and 9783 // ,34 seconds, or T36' 
23", 34 of the common division of the circle. The mean lati- 
tude of the arc is 51 0 25' 21". And the measure of 1 degree 
corresponding to it is 57068,41 toises. 
In the same manner the measure of the arc comprised be- 
tween Arbury Hill and the northern extremity at Clifton, is 
70377,85 toises, and 4438,63 seconds, or i° 13' 58", 6$. Its 
mean latitude is 52 0 50' 32". And we have for one degree of 
the meridian, corresponding to this latitude, 57080,70 toises. 
Hence, if we divide the entire arc into two equal parts, we 
deduce the following values of a degree corresponding to the 
middle of the whole and of its parts. 
Latitudes. 
51° 25' 20" 
52 2 20 
5° 30 
57°74t 
57^1 
