three Degrees of the Meridian. 29 



Latitudes. 

 51° 23 20" 57068 



52 2 20 57074 



52 50 SO 57081 



These values are, as appears, perfectly in conformily 

 with the theory, and with the results of other measures 

 that have been taken in different parts of the northera 

 hemisphere: but, in order to place that agreement in a 

 more distinct point of view, I shall show how nearly these 

 estimates aL^ree with the elliptic hypothesis, by comparmg 

 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 obser- 

 vations, 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 nearlv in the meridian of the two extremities 

 at Dunnose and Clifton. It was, in all probability, this 

 circumstance which determined the author to observe the 

 latitude of Arbury Hill, as he would then have two partial 

 arcs independent of the whole and of each other. 



For determining the angular extent of these arcs, Lieut. 

 Col. Mudge observed the zenith distances of several stars 

 on the meridian above the pole, by means of a large zenith 

 sector constructed by Ramsden with the same pains that 

 he had bestowed upon the theodolite. Lieut. Col. Mudge 

 paid all possible attention, and took all such precautions as 

 mii^ht naturally be expected from an observer of his ex- 

 perience and address. Nevertheless the results of his ob- 

 servations made on different stars, differ no less than four 

 seconds from each other. But, by taking a mean of all, 

 the dimensions of the three arcs reduced to the centre at 

 each station are as follows : 



Between Clifton and Dunnose 2° 50' 23",33 

 Clifton and Arbury 1 14 3 ,40 



Arbury and Dunnose 1 36 19 ,95 * 

 The extent of the first arc, in linear measure, is 1036339f 

 feet English, and when this is reduced to toises, we have 

 for the lengths of the three arcs from Lieut. Col. Mudge's 

 measures, 



From Clifton to Dunnose 162067,3 

 Clifton to Arbury 70380,2 



Arbury to Dunnose 91 687,1 



These 



