\-OL. XLII.] PHILOSOPHICAL TRANSACTIONS. Qgg 



to be kept in their archives here, and also in those of the Royal Academy of 

 Sciences at Paris, standards of the yard measure, as also of the Troy and 

 Avoirdupois weights; an account of which was published in these Transactions, 

 N" 465; it was not the intention of the Society to determine what was the 

 absolute legal length of the yard, or the real and legal weight of the said several 

 pounds; but only to preserve, in those respective places, 2 measures, and 2 sets 

 of those weights, sufficiently near to what were in common use, and agreeing 

 with each other, for the purpose of comparing together, by a certain standard, 

 to which recourse might be had in either kingdom, the success of such exjje- 

 . riments made, either in England or in France, in which measure or weight 

 might particularly be concerned. 



The gentlemen also of the Royal Academy of Sciences, took care to have 

 the length of their half toise set off on both the brass rods, on which the Eng- 

 lish yard had been already laid off, and provided 2 brass weights of 2 French 

 marcs each ; one of which was sent over hither, when one of the brass rods, 

 just mentioned, was again returned over to the Society. And it was the pro- 

 portion only between these several standards, that w.hs proposed to be laid down 

 in the said paper published in these Transactions ; without intending to ascertain 

 the just and legal proportions between the weights and measures of both na- 

 tions. Though it is not to be doubted, but that this measure of the French 

 half-toise, and the French 2 marc weight, are, like the English, sufficiently 

 agreeable to what are there constantly used. 



But as some gentlemen have since wished to know, how far those standards 

 agreed with what are esteemed the original ones, in the Chamberlain's Office of 

 his Majesty's Exchequer, as well as with those kept for public use, at Guild- 

 hall, at Founders'-hall, with the Watchmakers' company, and in the Tower of 

 London, Mr. George Graham, F. R. S. was requested to take upon him the 

 comparison of the said several standards; which he has accordingly done, and 

 carefully viewed and examined the same at the Exchequer, in the presence of 

 the president of the Society, the Earl of Macclesfield, Lord Charles Cavendish, 

 John Hadley, Esq. William Jones, Esq. Peter Daval, Esq. and Cromwell 

 Mortimer, M. D. and at Guildhall, Founders'-hall, and the Tower, in the 

 presence of all the same persons, Mr. Daval only excepted, who happened to 

 be otherwise engaged that day. 



Aiid as the council of the Society have now thought fit to direct an account 

 to be here published of these trials and experiments: we shall first begin with 

 the measure of the yard ; and then proceed to what concerns the several weights 

 of the Troy and Avoirdupois pounds. 



The standards of length now used in the Exchequer, are 2 squared rods of 



4u 2 



