MERIDIAN ON THE COAST OP COROMANDEL. 141 



reefed under the frame of the zenith sector. When 

 the tent was removed, a large bamboo flag-staff was 

 erected, whose cavity covered the picket, and in that 

 state it remained until the measurement was com- 

 pleted. 



At the termination of the base, being the end of a 

 chain, one of the large hooped pickets was driven 

 into the ground till its top was on a level with the 

 coffers and under the arrow of the chain. The op- 

 posite end being adjusted by the finger screw, the 

 arrow at the leading end was nearly the center of the 

 picket. A mark was made^ and a small round headed 

 nail was driven in till it was level with the surface. 

 The chain was again applied, and the arrow cut the 

 center of the nail. The picket had been driven up- 

 wards of two and a half feet into very hard clay. 



But that those extremities may be preserved, in 

 case they may hereafter be referred to, I erected small 

 masses of hewn stone eight feet square at the bottom 

 and four at the top, the axis of those masses being 

 made to pass through the points of commencement 

 and termination, and in order that this might be cor- 

 rectly done, the following method was used. 



I marked ont the foundation of the building, so 

 that the picket might be as nearly in the center of it 

 as possible. The earth vv^as dug about a foot deep, 

 reserving a space round the center untouched. After 

 the foundation was brought to a level with the sur- 

 face, the first tier of stones was laid, being one foot 

 in height. The inner part was then filled up with 

 scones and mortar, taking particul.ir care at the same 

 time that the center was not touched. Tl)e next tier 

 of stones was then laid, which was six feet square and 

 one foot high. This also was filled in with great 

 care, and some cement and bricks put gradually 

 round the picket. After that the last tier was laid 

 which was four feet square and also one foot high. 



