to ascertain a Standard of Weight and Measure. 169 
Inches. 
The 1st of the preceding observations giving - - 36,0013 
The 2d - - 35,9933 
The mean length of Mr. Graham's standard becomes 35,997 3* 
agree with my ist and 3d comparison, but not with the intermediate one. See Phil. 
Trans, for 1768, p. 324. 
As I am now upon the subject of foreign measure, it may not be quite out of place 
to say a word on the length of the ancient Roman foot, which I am enabled to do 
with some precision. 
Some years ago, when I was in Italy, I had several opportunities of ascertaining the 
length of this measure, by actual examination of the Roman foot rules, of which I 
have met with nine, viz. two in the Capitol at Rome ; one in the Vatican; five in the 
Museum at Portici, near Naples; and lastly, one in the British Museum, sent from 
Naples by Sir William Hamilton. They were all of brass, except one half-foot, of 
ivory, with a joint in the middle, resembling our common box or ivory rules : and, by 
reference to my journal kept at that time, I find the mean result from all the nine 
rules, viz. by taking both the whole and the parts of each, (for they were divided into 
12 inches, and also into i6ths, or digits,) gave, for the length of the old Roman - 
foot, in English inches, correspondent to Mr. Bird’s measure, — 11,6063- 
In confirmation also of this conclusion, and agreeably to the idea of Mons. De la 
Condamike, in the “ Journal of his Tour to Italy”, I took the dimensions of seve- 
ral ancient buildings, viz- the interior diameter of the temple of Vesta ; the width of 
the arch of Severus ; the door of the Pantheon ; and the width of the base of the 
quadrilateral pyramid of Cestius, which, it is curious to observe, I found exactly 100 
old Roman feet, and 125 feet high. This I do not remember to have seen noticed by 
any former traveller. 
The mean result of these experiments gave me - 1 1,617 English inches. 
Ditto, as before, from the rules - 11,606 ditto. 
The mean of the two modes of determination is - 11,612 ditto. 
I may add, that in the Capitol is a stone, of no very ancient date however, let into 
the wall, on which is engraven the length of several measures, from whence I took the 
following : 
The ancient Roman foot, 11,635 English inches. 
The modern Roman palm, rr: 8,82 ditto. 
The ancient Greek foot, — 12,09 ditto. 
z 
MDCCXC VIII. 
