Chap. VI.] Mathematics. 79 



The attempt made in France, witliln a few years 

 past, to form a standard of length, weight, and 

 capacity, by measuring a certain number of de- 

 grees on a great circle of the earth, is generally 

 known*. This plan is considered, by good judges, 

 as having some important advantages j though ia 

 simplicity and practicability it is certainly inferior 

 to the one last mentioned. 



The last century is also eminently distinguished 

 for the production of various kinds of Tabtes, which 

 are of the utmost importance to the mathemati- 

 cian, particularly in giving facility and precision 

 to his calculations. Such of these as pertain im- 

 mediately to astronomy were mentioned in a for- 

 mer chapter. Beside these may be enumerated 

 the tables of LogarltJnnSy of Sines and Tan- 

 gents, of Difference of Latitude and Departu?T, 

 of Meridional Points, of Loxodromic or Rhumb 

 Lines, all of which, and many more, ha\e been 

 brought to a degree of perfection, during this 

 period, which was never before known. The ta- 

 bles more particularly entitled to honourable 



* The liietliod adopted by the French Institute for obtaining an 

 invariable standard of measure is, to assume a certain portion of 

 the whole circumference of the earth. For this purpose tbey 

 actually measured, on a great circle of the earth, the distance be- 

 tween Dunkirk and Barcelona. The portion of the meridian from 

 Dunkirk to Rodez was measured by Delambre ; and tiiat from 

 Rodez to Barcelona, by Mechain. From this measurement the 

 length of the whole meridian was easily calculated 5 after which 

 a certain portion of the whole circle {i\ forty 'millionth) was fixed 

 upon as the standard of measure. This standard tlie French call 

 the Metre, which is about equal to 39.3/1 EnglijU inches. 



