gJ4r MEASURE OP A DEGREE ON THE COROMANDEL COAST, 



vity of the bamboo. That being adjusted, lines were drawn 

 on the tops of the pickets where the threads had been ex- 

 tended. The building was then erected, and the centre 

 both of the second and Inst tier was marked by the inter- 

 section of those threads, when applied to the marks on the 

 pickets. 



Such has been the mode of defining the extremities of the 

 line. The buildings are well built of stone and some brick, 

 and will remain for years, if not injured by acts of violence. 

 They are intended to receive an instrument on the top, and 

 the points are points of reference, if it should ever be jthought 

 necessary to have recourse to them. 



Expansion of the chains, and their comparative lengths. 



Comparison of ^ s ' wished to be satisfied with respect to the expansion 

 the chain used of each of the chains, and their comparative lengths, I made 

 ^indarcT* a course °^ experiments for both purposes. I had accord- 

 ingly the coffers arranged near the ground, that the drawing 

 and weight posts might be driven deep and firmly fixed. 

 Both the chains were then put into the coffers, and the com- 

 parisons made as follows : 



April 10, at 6 P. M. the temperature by a mean of five 

 thermometers was 85 0, 6. 



Three comparisons were made, and the old chain ex- 

 ceeded the new one, nine divisions of the micrometer screw. 



April 10, at 6 A. M. the temperature by a mean of five 

 thermometers was 79°- 



Four comparisons were made, and the old chain exceeded 

 the new one nine divisions. Therefore at the commence- 

 ment, the old chain exceeded the new one in length, nine 

 divisions of the micrometer. 



May 23. After the base was completed, the temperature 

 by a mean of five thermometers, was 86°. 

 By a mean of five comparisons, 

 the old chain exceeded the 



new one 10*65 divisions. 



24. The temperature by a mean of five 

 thermometers was 84°. 



And 



