g6S SURVEY OF THE COASt 



value in terms of the mean distance of the scale, according 

 to the principle of the En,a;lish standard. This was effect- 

 ed by about fifty measurements with an unahered micros- 

 cope, and gave the distance used, 79",8 — i",0=78",800i72 

 of the mean value of the scale. To this distance all the va- 

 lues obtained in the metre comparisons were ultimately re- 

 ferred. 



To shorten the mode of registering the results, the com- 

 bination of the metres, and their position, the following no- 

 tation was adopted : — 



M " denotes The iron metre of the Committee of Weights and Measures 



in Paris. 



M' The iron metre of Lenoir. 



M* The brass metre of Lenoir. 



M y The iron bar which I intended to bring to the metre length. 



M'^-h' The metre of the Committee and that of Lenoir added to- 



gether, — all m.irks being upwards. 



M.o+j The same metres, — all marks being downwards. 



In like manner, in the other combinations, the addition of 

 the special marks at the top, always denotes the sum of the 

 metres so indicated, and the inversion of these letters the 

 inversion of those metres. 



On the 13th of March, early in the morning, the eleven 

 thermometers, which remained on the scale during the pre- 

 ceding night, were read ; and after having assured myself 

 that all was in good order, 1 observed the comparisons in- 

 serted in the following table : — 



