MERIDIAN ON THE COAST OF COROMANDEL. 147 



putation, which was thought less necessary, since 

 the whole deduction did not amount to three 

 inches. Neither was any notice taken of the dif- 

 ferent heights of the hypothenuses or levels one 

 above another, as that difference was too trifling 

 to affect a length of thirty or forty chains. The 

 base has therefore been considered at the same dis- 

 tance from the center of the earth, before it was 

 reduced to the level of the sea, and the perpendi- 

 cular height of the south extremity, which I have 

 considered as nearly the general height, has been 

 taken for that purpose. That perpendicular height 

 was obtained by comparing the south with the north 

 extremity, and the height of the latter was deter- 

 mined by observations made at the race-stand and 

 on the sea-beach, where allowance has been made 

 for the terrestrial refraction. The following is the 

 manner in which it has been determined ; 



On the top of the race-stand, the under part of 

 the flag on the beach was observed to be depressed 

 9' 30" ; and at the beach, the top of the race-stand 

 was elevated 7' 15". When the instrument was on 

 the platform of the race-stand, the axis of the te- 

 lescope was on a level with the top of the railing, 

 which was observed from the beach. But at the 

 beach the axis of the telescope was four feet below 

 the part of the flag which had been observed. 



Tlie horizontal distance from the station on the 

 stand to that on the beach is= 19208 feet. Then 

 as 19208 : 4:: Had : tan. 43", which must therefore 

 be added to the observed depression of the flag — • 

 Hence 9' 30 +43"= 10' 13" is the depression of "the 

 axis of the telescope on the beach, observed from 

 the race-stand. 



Now the station on the beach is nearly at right 

 angles to the meridian, therefore, by allowing 



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