704 



PHILOSOPHICAl, TRANSACTIONS. 



VII. A. 



AN° - 



I^ANNO 1743. 



E. L. 



1588. 



A° KEG. XXX. 



With which are also kept a pile of flat Avoirdupois weights, from J 4 pounds 

 down to the 64th part of a pound. 



When the Avoirdupois weight came first to be esteemed a lawful weight, does 

 not appear ; but by these standards it is plain it has been used as such ever since 

 the reign of Queen Elizabeth. And as the weight of 15 pounds Avoirdupois 

 has before been made use of, in determimng the proportion between the weight 

 of this pound and that of the pound Troy, we shall begin by giving the 

 counterpoise of the said 15 pound Avoirdupois, as it was found in Troy weight: 

 from whence we shall deduce the proportions of those pounds, and afterwards 

 compare the same with the like proportions, deduced from the 7 pounds, and 

 single pound bell-weights, and the single pound flat weight abovementioned : 

 all which weights were taken in the presence of the above-named noblemen and 

 gentlemen, by Mr. Samuel Read, scale and weight-maker near Aldersgate, who 

 brought to the Exchequer a large balance of his own for that purpose, and 

 which, when loaded with 15 pounds at each end, was very readily turned with 

 6 grains; as a less one, he brought also for examining the single pound weights, 

 was with half a grain. He also brought with him what he called his own 

 standard penny and grain weights, 10 supply what was necessary to make the 

 counterpoise of the Exchequer weights : with all which the result was, that 



The standard 14 pound, and single pound Avoirdupois weights, taken to- 

 gether, were, on a medium of 4 trials, alter counterchanging the weights in 

 each basin, changing the basins, and then again counterchanging the weights, 

 found to be counterpoised by 218 Troy ounces, 13 penny-weight, 23 grains 

 and 4th. from whence the Avoirdupois pound is deduced equal to 6998.35 of 

 such grains as the Troy ounce is reputed to contain 480 of; and the Avoirdu- 

 pois ounce, of which 16 are supposed to make a pound, is found equal to 437.4 

 like grains. 



Again : the 7 pound bell Avoirdupois weight, with the same scales, and on a 

 medium of 4 like experiments, counterchanging, as before, both vveights and 

 basins, was found to be counterpoised by 102 Troy ounces 1 penny-weight, 

 and 21 grains. According to which, the Avoirdupois pound conies out equal to 

 7000.7, and the ounce to 437-54 Troy grains. 



