MEASURE. 
598 
to fuperfidal and folid meafures; taking for the unit of 
the former the fquare of the decuple, and for that of the 
latter the cube of the tenth part of the metre. They chofe 
alfo, for the meafuring unit of weight, the quantity of 
diftilled water equal in bulk to the fame cube in a con- 
flant ftate prefented by nature, viz. of a certain tempera¬ 
ture. And laftly, it was decided, that the multiples and 
fubmultiples of each kind of meafure, whether of weight, 
capacity, furface, or length, (hall be always taken in the 
decimal or decuple progreflion, as the molt fimple, natu¬ 
ral, and eafy for calculation, according to the fyllem of 
numeration which all Europe has ufed for many centuries. 
As the bafis of this new metrical fyftem depends on a 
quarter of the terreftrial meridian, it was necelfary that 
the magnitude of this arc fliould be known to great pre- 
cifion. Therefore, although many different degrees of the 
meridian had been carefully meafured at feveral times, 
and in different countries, the Inftitute ordered a new 
and aCtual meafurement of the whole arc of the meridian, 
extending the whole length of France, viz. from Dunkirk, 
on the north, to Barcelona in Spain, and paffing through 
Paris; an extent of almoit ten degrees. The meafure- 
ment of this arc, in feveral years, was at length completed 
by Mechain and Delambre, two eminent altronomers; in 
which they employed rules or rods made of platina, of 
two toifes or n feet in length, for meafuring the bafes ; 
and whole circles, accurately made, for taking the angles, 
to tenths of feconds, by repeating the meafures in many 
different parts of the circumference, and taking mediums 
of the whole. The precifion with which the angles were 
obferved is fuch, that out of 90 triangles which connect 
the extremities of the meridional arc, there are 36 in which, 
the fuin of the three angles differs from its proper quan¬ 
tity by lef's than one fecond ; that is, in which the error 
of the three angles, taken together, is lefs than one fecond. 
Every care was taken to fupport and difpofe the platina 
rods properly in meafuring the bales. The extremities of 
the rods were never brought into contact; an interval 
being left, wJiich was meafured by a tongue of platina, 
Aiding from the end of one of the rules, and carrying a 
vernier and microfcope. The corrections or allowances 
for differences of temperature, for obliquities of the line 
actually meafured, and for the elevation above the level 
of the fea, were alfo attended to, and allowed for. One 
rod was kept unemployed, for a module or ftandard, which 
was exaCtiy equal to the double toife of Peru, in ten de¬ 
grees temperature of Reaumur’s thermometer, or fifty-four 
of Fahrenheit. With this module, and alfo with the toife 
of Peru, the other meafuring-rods were compared, both 
before and after the operations of meafuring, and found 
not to be at all altered. 
The fettling the article of the meafure of weight was 
deputed to Lefevre Gineau, together with Fabroni of 
Florence; and the calculations from the meafures of Me- 
chain and Delambre, and the management of the whole 
bufinefs, were under the direction and conduCt of a num¬ 
ber of commifiioners, feveral of whom were deputed from 
ether nations: their names were FEneae, Balbo, Borda, 
BrifTon, Bugge, Cifcar, Coulomb, Darcet, Delambre, Fa¬ 
broni, La Grange, La Place, Lefevre-Gineau, Legendre, 
Franchini, Mafcheroni, Mechain, Multedo, Pederayes, 
Prony, Tralles, Van Swinden, and Vaflali. 
The divifions of the new weights and meafures adopted 
by the French republicans, and the names which they 
.have given to them, are fimple, and eafy to be remembered ; 
they are Greek words latinized, made French, and readily 
affimilate with other tongues. The following table fhows 
the whole fyftem in a clear and diftinCt point of view, as it 
was eftablilhed by a decree of the national Convention on 
the 7th of April, 1795, 
Relation oj 
the Meafures 
to Unity. 
Long 
Meafure. 
Superficial 
or Land 
Meafure. 
So lid Med pure 
of Wood for 
Fuel. 
Capacity Dr. 
and Liquidy 
I OOOO 
IOOO 
Myriametre 
Chiliometre 
Myriare , 
Chilioftere 
Chiliolitre 
100 
Hectometre 
Hectare 
Hectollere 
HeCtolitre 
10 
Decametre 
Decare 
Decaftere 
Decalitre 
I 
Metre 
Are 
Stere 
Litre 
0*1 
O'OI 
O'OO ! 
Decimetre 
Centimetre 
Millimetre 
Deciare 
Centiare 
Dcciltcre 
Decilitre 
Centilitre 
In the 8th Number of the Journals of the Royal Infti- 
tution, we have a detailed account of the coinparifon of 
the French definitive metre with an Englilh ftandard. A 
ftandard metre of platina, and another ftandard of iron, 
belonging to the National Inftitute, were thus compared 
with the EngJifh foot; each of thefe two meafures being 
equal, at the temperature of melting ice, to the ten mil¬ 
lionth part of the quadrant of the meridian. At the tem¬ 
perature of s°^° of Fahrenheit, the metre of platina was 
equal to 39*3775 Englifh inches; and that of iron to 
39*3788. At the temperature of 55 0 , the platina ftandard 
was 39*3781, that of iron 39.3795. 
From thefe and various other experiments and calcula¬ 
tions, the French metre or ftandard appears to be equal 
to 39*3710 Englilh inches, at 62°, which is the tempera¬ 
ture univerfally employed in the comparifon of Britilh 
ftandards. Allowing the accuracy of the French mea- 
fureinents of the arc of the meridian, the whole circumfer¬ 
ence of the globe will be 24855*43 Englilh miles, and its 
mean diameter 7911-71. Taking the ellipticity at 
the axis will be nearly 7893*5, the equatorial diameter 
7928, and the diameter of a fphere of equal folid content 
about 7916 miles. As long, therefore, as the Englilh 
ftandard continues to be reduced to this temperature, we 
mult conlider the metre as equivalent to 39'37io inches. 
Upon thefe authorities, it will be of ufe to give the fol¬ 
lowing Tables of the principal meafures and weights now 
ufed in France, with the corrections which this laft com- 
parifon has introduced into it. 
Meafures of Length in Fnglfih Inches. 
Millimetre . . , 
. *03937 
Centimetre . . . 
• 
• 
.39371 
Decimetre , 
• 
. 3937*0 
Metre . . , . 
0 
393710Q 
Decametre . . 
« 
393*71000 
HeCtometre . , 
, 
3937*10000 
Chiliometre . 
• 
• 
39371*00000 
Myriometre . . 
• 
3937 io - o°ooo 
Mile. 
Fur. 
Yd. Ft. In. 
A decametre , 
0 
0 
IQ 2 9:7 
A hecatometre . 
« 0 
0 
J09 I I 
A chiliometre 
0 
4 
213 I IQ2 
A myriometre 
3 chiliometres are nearly 5 miles. 
. 6 
1 
156 0 6 
Superficial or Land Meafures. 
Are, a fquare decametre 119*6046 fquare yards. 
Decare . . 1196.0460 
Hecatare . . . 31960*4600 
Solid Meafure of Wood for Fuel. 
Deciftere, for fire-wood . 3 * 53*7 cubic feet, 
Srere, a cubic metre . » 35 ' 3 s 7 o 
Pecaftere , » • 
Mea/urqi 
