110 LECTURE X. 



of this quadrant was taken for the unit or metre. A standard was deposited 

 in the custody of the legislative body, adjusted at the temperature of melting 

 ice. In order to be able always to identify this length, without recurring to 

 an actual measurement of the arc, it was of importance to compare it very 

 accurately with that of the pendulum vibrating seconds, and this has been 

 done with great care by Borda, at the observatory of Paris. The unit of mea- 

 sures of land is the are, or 1 00 square metres : a cubic metre of wood is called 

 a stere, and a cubic decimetre, or a cube of which the side is one tenth of a 

 metre, is a litre, or measure of fluids. 



" Uniformity appeared to require that the day should be divided into ten 

 liours, the hour into a hundred minutes, and the minute into a hundred se- 

 conds. This division, useful as it will be to astronomers, is of less advantage 

 in civil life, where arithmetical operations are seldom performed on the parts 

 of time ; and the difficulty of adapting it to clocks and watches, together 

 with our commercial relations with foreign countries, have suspended its in- 

 troduction for the present. We may, however, expect that it will ultimately 

 be brQught into general use." 



Such is Mr. Laplace's account of the new system of measures, the result of 

 the joint labours of many of the ablest mathematicians on the continent. 

 There is not at present any great probability that it will ever be employed in 

 this country. It is of little consequence from what the original unit has been 

 derived, unless we can with ease and accuracy recur to its origin: and whe- 

 ther a standard has been first adjusted according to the circumference of tiie 

 globe, or to the foot of an individual hero, the facility of comparing other 

 measures with it is the same. It is confessed that the pendulum affords the 

 readiest method of recovering the standard when lost; and if it was necessary 

 for the Committee of the French Academy to determine a unit absolutely 

 new, it would perhaps have been more eligible to fix on one which was inde- 

 pendent of any ulterior comparison, than to seek for an ideal perfection in at- 

 tempting- to copy from a more magnificent original : to say nothing of the un- 

 certainty with regard to the ellipticity of the earth, and the probable irregu- 

 larity of its form in various respects. On the other hand, it must be allowed, 

 that the correct determination of the length of the pendulum has sometimes 



