W$ ^1 MEASURING APPARATUS OF THE ' 



establishing an universal system of weights and measures which should 

 . be common to all nations ; but it would obviously be necessary to that end, 

 that some unit, which nature afforded as a constant mark of reference, 

 should be fixed upon as the basis of the system ; now nature gives us 

 many lovely flowers and beauteous plants, and a thousand and a thousand 

 diversified shapes, but we can only cull from all her productions two units 

 which are at all accessible and unchanging. These are the lengths of the 

 pendulum in a given latitude, and of the meridional quadrant. The latter 

 of these accordingly was selected, and great pains were taken by the 

 French to deduce the exact distance from the Pole to the Equator by means 

 of the comparison of an Arc extending from Formentera to Dunkirk, with 

 the former measure of 1735, which I have above adverted to as having 

 been undertaken under the government of Louis XV. 



. "m The ten millionth part of the meridional quadrant thus found, was 

 taken as the future national standard unit of France, and called the 

 Metre. 



The old French measure was the toise of G Paris feet, and the two 

 iron bars of this denomination which went, one to the Polar circle, and the 

 other to the Equator in 1735, had been rigorously compared with each 

 other at the temperature of 13" of Reaumur ; one of these, called the 

 toise de I'Academie or toise de Perou, was still in good preservation, 

 but that which went to the North had been rusted in consequence of having 

 been shipwrecked in the guiph of Bothnia. 



13° of Reaumur is equivalent to 16]; of the scale of Celsius, or the 

 centigrade, and to 61°^ of Fahrenheit. The English standard temperature 

 is 62° of Fahrenheit. The temperature of the metre, or module, is zero of 

 the centigrade of Reaumur, and 32 of Fahrenheit. 



