MEASURE OF A DEGREE ON THE COROMANDEL COAST. 3 J J 



There were only four angles of depression, and two of Proceeding on 



elevation, taken in the whole length of the base; the rest ra j sin g° r lo ^- 



, enng the cof- 



were all horizontal measurements, and many of them consist fere. 



of a great number of feet before it became necessary either 

 to sink or elevate the coffers ; when that was done, great 

 care was taken to mark the termination of the preceding 

 measurement ; and for that purpose a small tripod was used 

 in the shape of a T, with three iron feet to run into the 

 ground, the straight side of which T was placed in the line. 

 Another small t was made with its top also parallel to the 

 line, and fixed upon the large one so as to slide to the right 

 or left, and upon that again was a long piece of brass made 

 to slide out at right-angles to the top of the T ; in the mid- 

 dle of this brass a mark was made, which was brought to a 

 plumb line let fall from the arrow, and the height from the 

 brass to the arrow was noted down ; when the succeeding 

 chain was laid, which was to commence the new level or 

 hypothenuse, the arrow was then brought so, that a plumb 

 line, freely suspended, would coincide with the mark on the 

 brass slider. The height of that chain above the brass was 

 likewise taken ; by comparing these two heights the eleva- 

 tion or depression of the new commencement was deter- 

 mined; and these differences noted in the seventh and 

 eighth columns of the table. The differences of the two 

 aggregates contained in these columns, when applied to the 

 ascents and descents, will therefore show how much one ex- 

 tremity of the base is above the other. The height of the 

 chain at the commencement and termination of the whole 

 was of course taken from the ground. 



All the other particulars respecting this measurement are 

 nearly the same as that in the Mysore country, a full ac- 

 count of which has been published in a former volume of 

 the Asiatic Researches. Some little alterations have been Coffers, 

 made in the coffers ; that is, they were all of the same length, 

 and the whole together about ninety-six feet, so as to give 

 room for the pickets with the brass register heads. Their 

 sides continued to the ends, and their depth on each side 

 was the same, for the purpose of being turned every day, 

 that they might not fall iuto a curve by their own weight and 

 that of the chain. I also used tripods with elevating screws 



in 



