i8s Sir George Shuckburgh Evelyn’s Endeavours, &c. 
And the probable error, in the divisions of this old standard, is 
about inch. 
(§• 5S-) ^ rnay now be desirable to see the comparative 
lengths oi these various standards and scales, reduced to one 
and the same measure, viz. Mr. Troughton’s. 
36 inches, on a mean, of Hen. VII. standard 
of 1490, are equal to 
Inches on 
Troughton’s. 
Diffe- 
rence. 
Probable error 
in divisions. 
35 > 9 2 4 
— ,076 
>03 
of standard yard of Eliz. of 1588 
36,015 
+ > 0l 5 
>04 
— of standard ell of ditto, of 1588 
36,016 
d - ,0 1 6 
,04 
*of yard-bed of Guildhall, about 
1660 - 
36,032 
+ » 03 2 
*of ell-bed of ditto, about 1660 
36,014 
+ .014 
*of standard of clock- makers’ 
company, 1671 
35 > 97 2 
— ,028 
*of the Tower standard, by Mr. 
Rowley, about 1720 
36,004 
+ ,004 
of Graham’s standard, by Sis- 
son, of 1742, viz. line E - ' 
36,0013 
+ ,0013 
of ditto, ditto, viz. line Exch. = 
35>9933 
— ,0067 
— — of Gen. Roy’s" 
(Bird’s) scale - 
of Mr. Au- 
bert’s, ditto, ditto 
- — — of Royal So- 
ciety’s ditto, ditto _ 
all made, pro- 
bably, between 
the years 1745 
and 1760. 
|*= 36,00036 
< = 35 > 99 88 ° 
[=35,99955 
+ ,00036 ,0003 
— ,00120 ,000 6- 
— ,00045 > 00 °4 
— of Mr. Bird’s parliamentary 
standard, of 1758 - =36,00023 +,00023 
■ * of Mr. Tro u ghton’s scale, 
in 1796 - _ - =36,00000 ,00000 ,0001. 
From hence it appears, that the mean length of the standard 
yard, taken from the seven first instances in this table, agrees 
with the quantity assumed by Mr. Bird, or Mr.TRouGHXON, to 
within y-ooo inch, but that the latter is the longest. 
* These four quantities are taken from Mr. Graham’s account, in the Phil. Trans. 
Vol. XLII. 
