aSo Notices refpeBing New Booh. 



liOied. Now, it very frequently happens, that forfie of thefe 

 operations arc carried a little too far, and one or two of the 

 weights rendered fomewhat too light ; and when this is the 

 cafe, unlefs the workman can beabiolutely depended on, the 

 whole fet will infallibly be fpoiled ; for, in ftead of making 

 new ones to fupply their place, he will, nine times in ten, 

 prefer the adjufting the others to them ; conceiving it to be 

 of more confequence that they fliould all agree, than that they 

 Ihould be accurately of any particular weight. When weights 

 are fucceffively copied from each other a number of times, 

 the lad of the feries will therefore frequently be lighter than 

 the firft, and fometimes very confiderably fo. 



"For the appreciation of the weight in troy grains of a cubic 

 inch of diftilled water at 60", from the experiments of the 

 French commiffionerj of weights and meafures, we have the 

 following data. 



" We are told by the InJlruBmi fur les Voids & Mefures^ 

 prefixed to M, Briflbn's Traite de Vhyjique, and which is cer- 

 tified by the commiflioners to be " exa6tly founded on the 

 refults obtained and recorded by the faid commiffion," and 

 in feveral other works, that they weighed dillilled water in 

 nine different cafes at various temperatures, in air and in 

 vacuo. We will, however, feleft the cafe which they have 

 thought proper to affume as the bafis of their ftandard of 

 weight, viz. that in which the weight of water is taken at its 

 maximum of denfity (or about the temperature of 40° of Fahr.) 

 and in vacuo ; under which circumllances they inform us 

 that the cubic decimetre weighs a pounds 5 gros and 35'i5 

 grains, or 18827*15 grains of the poids de marc. 



" This, according to M. Tillet's appreciation of the Eng- 

 lifli troy poimd, which he makes equal to 7021 of thefe grains, 

 is equal to 15445'7 grains troy. 



*' Now, we find from the report made to the Mathematical 

 and Phyfical Clafs of the National Inftitute on the 27th of 

 December 1801 *, relative to a comparifon of the metre with 

 a fcale of M. Pidet's, which was exactly fimilar to that of 

 Sir George Shuckburgh Evelyn, that this meafure is equal to 

 39-38272 inches of that fcale when at 32^; or, correding for 

 temperature according to General Roy's table of the exjian- 

 lion of his brafs fcale, in the 75th volume of the Philofophical 

 'JVaufadions, equal to 39*37:2 inches of the fame fcale when 

 it 60°; the French plaiina and iron ftandards, when at the 

 freezing point, indicating the length of the metre. 



*' The cubic decimetre, therefore, is equal to 61*02896 



■'■ riiilolbphical Magazine, vol. xti. p. £29. 



cubic 



