MERIDIAN ON THE COAST OF COROMANDEL. 145 



I had made a great many experiments prior to 

 the measurement, but found great irregularity, 

 partly from not attending sufficiently to the above 

 circumstance, and partly from the unsteadiness of 

 the drawing post, notwithstanding it was driven 

 deep into very hard ground, and secured, as I 

 thought, by having large stones pressed close on 

 each side of it. To remedy this latter inconveni- 

 ence, I had a staple driven into a brick wall, into 

 which the iron was fixed with the adjusting screw 

 for the chain, after which I perceived a perfect 

 coincidence w^ith the arrow and mark on the brass 

 head, except what arose from the trifling expan- 

 sion and contraction of the iron which held the 

 chain. I then began a new course of experiments 

 on both the chains, and the results were as fol- 

 lows : — . 



EiXperimmts for determining the expansion of the 



new Chain. 



Vol. VIIL 



