VOL. XLII.] PHILOSOPHICAL TRANSACTIONS. 605 



other, might be laid up and preserved in the archives both of the Royal Society 

 here, and of the Royal Academy of Sciences at Paris : which proposal having 

 been received with the general approbation of both those bodies, they were 

 pleased to give the necessary directions for bringing the same into effect. In 

 consequence of which, Mr. George Graham, Fellow of the Royal Society, did, 

 at their desire, procure from Mr. Jonathan Sisson, instrument-maker in Beau- 

 fort-buildings, two substantial brass rods, well planed and squared, and of the 

 length of about 42 inches each, together with 2 excellent brass scales of 6 

 inches each, on both of which one inch is curiously divided by diagonal lines, 

 and fine points, into 500 equal parts; and on each of the rods Mr. Graham did, 

 with the greatest care, lay off the length of 3 English feet from the standard of 

 a yard kept in the tower of London. He also at the same time directed Mr. 

 Samuel Read, scale and weight maker near Aldersgate, to prepare, in the best 

 manner he could, 2 single Troy pound weights, with 2 piles of the same weight, 

 decreasing from 8 ounces to one quarter of an ounce respectively, 2 parcels of 

 the less corresponding weights, that is, from 5 dwts. to half a dwt., and grain 

 weights from 6 grains to one-fourth of a grain; with 2 single Avoirdupois pound 

 weights : all which, when made, were carefully examined, and found to agree 

 sufficiently with each other. Things being thus provided, the 2 brass rods, 

 one of the 6-inch scales, and one set of all the weights, were sent over to Paris, 

 one of the rods to be returned, and all the other particulars, to be presented 

 for their use, to the Royal Academy of Sciences there : who, on receipt of 

 them, desired the late M. Du Fay, and Abbe Nollet, both members of the 

 Academy, and also fellows of the Royal Society, to see the measure of the Paris 

 half-toise, containing 3 Paris feet, accurately set off on both the brass rods, in 

 like manner as the length of the English yard, containing 3 English feet, had 

 already been set off on the same. After which those gentlemen returned over 

 one of the rods to the Royal Society, with a standard weight of 2 marcs, or J 6 

 Paris ounces, accompanied with a proces verbal, or authentic certificate from 

 the proper office, of the due examination of them. 



The rod being returned, Mr. Graham caused Mr. Sisson to divide both the 

 measure of the English yard, and the Paris half-toise, each into 3 equal parts, 

 for the more ready taking off both the English and Paris foot from the same : 

 after which, both this rod and 2 marc weight, sent over from France, were, 

 together with the other particulars before mentioned, carefully laid up in the 

 archives of the Royal Society, where they now remain, as their duplicates do 

 in those of the Royal Academy of Sciences at Paris : but as, before they were 

 so laid up, an accurate examination and comparison of them was made by direc- 



