36S ACCOUNT OF TRIGONOMETRICAL 



Yerracoiidah, and the observed angles PSY and PYS, 

 ■\ve have, the tangent of lialf the sum of the first, to 

 the tangent of half tlieir difference, as the tangent of 

 half the sum of the second, to tangent of 2" 54' 9^5". 9% 

 their half difference : from which we get the greater 

 angle at S = 92" 47' 49"-25, and the less angle at Y 

 = 86' 58'57".41 thus corrected for computing sphe- 

 lically : and with these and co-latitudes, proceeding 

 as before, the angle SPY will be had = (f 59' 14".83, 

 and the perpendicular arc ■=: 0" 57' 44".86. But the 

 chord subtended by this arc is 350824 feet, and there- 

 fore the arc itself 350827.7 feet. Then, as SUlM^I 

 : 350827.7 feet :: 60' : 364510.8 feet, or 60751.8 fa- 

 thoms, for the length of the degree at right angles to 

 the meridian of Savendroog, as deduced from the dis- 

 tance between Savendroog and Yerracondah ; and the 

 length of the perpendicular degree deduced from the 

 distance between Savendroog and MuUapunnabetta 

 being 60743.8 fathoms, the mean of these two, or 

 60747.8 fathoms, may be considered as nearly the 

 true measure for latitude 12° 55' 10". 



If the ratio of the earth's diameters be taken as 1 

 : 1.003125, and the meridional degree in latitude 

 ir 59' 55" be 60494 fathoms; then, by using these 

 data, the computed meridional degree on the ellipsoid 

 in latitude 12^55' 10'' will be 60498 fathoms; with 

 which and the above ratio, the computed degree at 

 right angles to the meridian in the same latitude will 

 be had 60858 fathoms, which exceeds the measured 

 one by 110 fathoms nearly; so that we may infer 

 fVom this, either that the earth is not an eUipsoid, or 

 that this measurement is incorrect. 



The more we investigate this Interesting subject, 

 and the more ample means we employ to ascertain 

 the exact figure of the earth, the more seems to be 

 wanting to satisfy our research; and ifwe feel re- 

 luctant in giving up the elliptic hypothesis, because 

 it is consonant to that harn)ony and order with 

 which we are famihar, the discord which these re- 

 sults indicate, afford by no means sufficient evidence 



