250 COMPARISON OF THE FRENCH METRE 



lefs than is ftated in the report, and that they coincide within 

 an unit in the laft place of the decimals exprefhng their magni- 

 tudes, or one ten thoufandth of an inch. The ftandard of pla- 

 tina at the freezing point becomes equal to 39.37380, and that 

 of iron to 39.37370 Englifh inches on the fcale of brafsat 55°, 

 and the mean of thefe to 39.37100 Englifh inches at 62°, 

 which is the temperature that has been univerfally employed 

 in the comparifon of Britifh ftandards, and in the late trigo- 

 nometrical operations in particular. This refult agrees fur- 

 prifingly with Mr. Bird's determination of the lengths of the 

 toifes fent by Mr. Lalande to Dr. Mafkelyne, of which the 

 mean was 76.734 inches : hence the metre, having been found 

 to contain 36.9413 French inches, appears to be equal to 

 39.3702 Englifh inches : or rather to be either 39.3694 or 

 39.3710, accordingly as the one or the other of the two toifes 

 happens to have been the more correct ; we may therefore 

 give the preference to that which meafured 76.736 inches. 



Allowing the accuracy of the French meafurements of the 

 arc of the meridian, the whole circumference of the globe will 

 be 24855.43 Englifh miles, and its mean diameter 7911.73. 

 Taking the ellipticity at ^\^, the axis will be nearly 7893§, 

 the equatorial diameter 7928, and the diameter of a fphere of 

 equal folid content about 7916 miles ; the brafs flandard being 

 at the temperature of 62° of Fahrenheit. 

 Standard metre As long, therefore, as the Englifh flandard continues to be 

 at 62 . reduced to this temperature, we rauft confider the metre as 



equivalent to 39.3710, and not to 39.3827 Englifh inches. 



Upon thefe joint authorities it may be of ufe to reprint here 

 a table of the principal meafures and weights now ufed in 

 France, with the very flight corrections which this laft com- 

 parifon has introduced into it. In tranflating the French 

 terms into Englifh, we are fully at liberty to refcue them, in 

 fome meafure, from the barbarifms in orthography which have 

 been committed in forming them. 



Meafures of length, the metre being at 32°, the foot at 62°. 



Englifh inches. 

 French meafures Millimetre .... .03937 



ofIcngth ' Centimetre .39371 



Decimetre ----- 3.93710 



Metre 



