330 



FIGURE OF THE EARTH. 



5'](y]?,>1^ toises,, or 0082(5,34 fathoms, at the temperature of 

 16-1° of the centigrade thermometer, the latitude being 52" 

 2' 20 '. 



The station at Arbnry Hill happens to be very nearly irj 

 the meridian of Clifton and Danuose, and divides the interval 

 between them into nearly equal parts. The measures of that 



But by divid. 

 ing the whole 

 arc into two 

 nearly equal 



nonhem mean P^'^ °^ ^^^ ^'''^' which lies between Arbury and Dunnose^ is 

 deg. proves 

 57063,41 

 toises ; 



by the tables 9l67g,47 toises, and 97S3 ',34 seconds, or l" 36' 

 23",34 of the common division of the circle. The mean lati- 

 tude of the arc is 51" 25' 21". And the measure of 1 degree 

 corresponding to it is 57068,41 toisss. 

 and the ^" ^he same manner the measure of the arc comprised be- 



southern mean tween Arbury Hill and the northern extremity at Clifton, is 

 fSe7^^^^°'^^ 70377,85 toises, and 4438,03 seconds, or r 13' 58'',63. Its 

 mean latitude is 52° 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. 



and the 

 degrees 

 increase in 

 going 

 northward. 



Latitudes. 

 51° 25' 20" 

 52 2 20 

 52 50 30 



5706S 

 57074 

 57O8I 



in perfect These values are, as appears, perfectly in conformity with 



Sth dSeory ^^^ theory, and with the results of other measures that have 

 an«i the results been taken in different parts of the northern hemisphere ; but, 

 in order to place that agreement in a more distinct point of 

 view, I shall show how nearly these estimates agree with the 

 elliptic hypothesis, by comparing them with those measures 

 of a degree, on which we can place the greatest reliance for 

 exactness. 



Now, if we compare the results of these calculations with 

 those deduced by Lieut. Col, Mudge from his observations, we 

 shall see the probable source of those errors, which it appears 

 to me have led him to false conclusions. It has already been 

 observed, that the station at Arbury Hill divides the whole 

 arc into two parts nearly equal, and that it is also nearly in 

 the meridian of the two extremities at Dunnose and Clifton. 

 It was, in all probability, this circumstance which determined 



the 



of other ad- 

 measurements 



Inquiry into 

 the errors 

 which led to 

 the former 

 conclusions. 



