VOL. LXXXVIII.] 



PHILOSOPHICAL TRANSACTIONS. 



307 



Exchequer standard of 1588. 



Differ, 

 from 

 Trough- 

 ton. 



Inch. 



— .007 

 + .063 



— .008 

 4- .022 



— .055 



— .036 

 + .032 

 + .017 



— .001 

 4- .051 



Length in 

 Inches 



35.993 

 18.063 

 26.992 

 31.522 

 33.695 

 44.964 

 22.532 

 33.767 

 39.374 

 42.239 



Differ, 

 on 36 

 inches. 



— .007 

 + .126 



— .011 

 4- .025 



— .059 

 -.029 

 + .052 

 4- .018 



— .001 

 4- .043 



Mean difference on 36 inches. 



Inch. 

 •= 4- 0.015 



+ 0.016 



I Viz. the Exchequer measure is by so 

 J much the longer, or about 1 in 2322. 



Entire yard 



I yard, from 24 to 42 inch. . 

 I yard, from 15 to 42 inch. . 

 ■J yard, from 10| to 42 inch. 

 •f| yard, from 8| to 42 inch. 

 Entire ell, from 2 to 47 inch. 

 I ell, from 2 to 24^ inch. . . 



|, from 2 to 35| inch 



{, from 2 to 41.375 inch 



f£., from 2 to 44.1875 inch. . 



It appears then, from this table, that the ancient standards of the realm differ 

 very little from those that have been made by Mr. Bird, or Mr. Troughton, and 

 consequently, even in a finance view, nothing need be apprehended, of loss in the 

 customs, or excise duties, by the adoption of the latter. 



I shall now endeavour to show the proportion of the weights that I have used, 

 compared with the standards that were made by Mr. Harris, Assay Master of the 

 Mint, under the orders of the House of Commons, in the year 1758. They are 

 kept in the same custody with Mr. Bird's scales of length, and appear to have been 

 made with great care, as a mean result from a great number of comparisons of 

 the old weights in the Exchequer, which have been detailed at length in that report. 

 Mr. Harris having been of opinion that the Troy pound was the best integer to 

 adopt, as the standard of weight, I venture to conclude that this was the most 

 accurate, and most to be depended on, of all the various weights and duplicates 

 that he made for the use of this committee; for he made them of 1, 2, 4, 8, 

 16 lb. and of 4-, 1, 2, 3, 6oz. It will therefore be sufficient for my purpose, to 

 compare the 1 and 2 pounds Troy, and their duplicates, with the weights of Mr.. 

 Troughton. I did this, June 2d, 1797; the barometer being at 29.72 inches, 

 and thermometer 67 . The result of which was, that 



The mean weight of 2 lb. Troy, is 11 527.70 grs. 



And consequently 1 lb. becomes 5763.85 



But, from the exam, of the 2 single pound weights, lib. is 5763.7 1 



Therefore the mean of all is =s 5763.78 



That is, Mr. Troughton's weights are too light by -vrdy.^l — 0.6562 

 grain on 1000 grs., or 1 in 1523.92 grs. 



In conclusion, it appears then, that the difference of the length of two pendu- 

 lums, such as Mr. Whitehurst used, vibrating 42 and 84 times in a minute of 

 mean time, in the latitude of London, at 1 1 3 feet above the level of the sea, in 

 the temperature of 60°, and the barometer at 30 inches, is as 59.89358 inches of 

 the parliamentary standard; whence all the measures of superficies and capacity are 

 deducible. That, agreeably to the same scale of inches, a cubic inch of pure dis- 

 tilled water, when the barometer is 29.74 inches, and thermometer at 66°, weighs 



rr 2 



