MERIDIAN ON THE COAST OP COIIOMANDEL. 14S. 



EXPANSION OP THE CHAINS and thbir COMPARATIVE 

 LENGTHS. 



As I wished to be satisfied with respect to the ex- 

 pansion of each of the chains, and their comparative 

 lengths, I made a course of experiments for both 

 purposes. I had accordingly the coffers arranged 

 Xiear 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 six P. M. the temperature by a mean 

 of five thermometers was 85°,6. 



Three comparisons were made, and the old chain 

 exceeded the new one, nine divisions of the micro- 

 meter screw. 



April 10, at six 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 commencement, the old chain exceeded the new 

 one in length, nine divisions of the micrometer. 

 May 23. After the base was completed, the tem- 

 perature by a mean of five thermometers^ 

 was 86°. 

 By a mean of five com- 

 parisons, the old chain 

 exceeded -the new one 10,65 divisions. 

 24. The temperature by a mean 

 of five thermometers 

 was 84°. 

 And a mean of six compa- 

 risons, gave the excess 

 of the old chain above 

 the new one - - - 1 1 ,08 do. 

 2^. The temperature was 87°. 



And a mean of two com- 

 parisons, gave - - 11,00 do. 



Mean 10,86 do. 



