a Standard of height and Meafure. tot 



inches. 



mine, by — 0,00127" 

 >ooi35 

 ,00128 'f = the total length therefore 36,00130 inches, the therm, at 6o*',8. 



Mean = ,00130^ 

 The interval on the line marked Exch. was fhorter than mine 



inches. 



bjr - — ,0066' 



,0066 

 ,0068 



= the total length = 35,9933 inches, the 

 therm, at 6o'',6. 



,0067^ 



And the Paris half-toife, which had been fuppofed by the Academy to be = 38,355 Englifli 

 inches, was found, compared 



inches. inches, 



with mine, to be = _ 



' Mean = 38,3561 *. 



* Dr. Mafkelyne fays, this ftandard yard of Mr. Graham's was ,„^„5 inch longer on three feet than Mr. 

 Bird's divided fcale, which he generally made ufe of in all his operations of dividing ; and, from one made 

 conformably to this of Mr. Bird's, Mr. Troughton divided my fcale of 60 inches. This remark feems to 

 agree with my ift and 3d comparifon, but not with the intermediate one. See Phil. Tranf. for 1768, p. 324. 

 As I am now upon the fubjeft of foreign meafure, it may not be quite out of place to fay a word on the 

 length of the ancient Roman foot, which I am enabled to do with fome precifion. 



Some years ago, when I was in Italy, I had feveral opportunities of afcertaining the length of this meafure, 

 by aflual 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 mufeum at Portici, near Naples ; arid, laftty, one in the Britifh mufeum, 

 fent from Naples by fir William Hamilton. They were all of brafs, except one half-foot, of ivory, with a 

 joint in the middle, refembling our common box or ivory rules : and, by reference to my journal kept at that 

 time, I find the mean refult from all the nine rules, viz. by taking both the whole and the parts of each (for 

 they were divided into li inches, and alfo into i6ths, or digits), gave, for the length of the old Roman 

 foot, in Englifli inches, ^correfpondent to Mr. Bird's meafure, := 11,6063. 



In confirmation alfo' of this conclufion, and agreeably to the idea of M. de la Condamine, in the '< Journal 

 of his Tour to Italy," I took the dimenfions of ftveral ancient buildings, viz. the interior diameter of the 

 temple of Vefta ; the width of the arch of Severus ; the door of tKe Pantheon ; and the width of the bafe 

 of the quadrilateral pyramid of Ceftius, which, it is curious to obferve, I found exaftly lOo old Roman feet, 

 and 145 feet high. This I do not remember to have feen noticed by any former traveller. 



The mean refult of thefe experiments gave me - - . - 11,617 Englifli inches. ' 



Ditto, as before, from tlie 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 ftone, of no very ancient date however, let Into the wall, on which is 

 engraven the length of feveral meafures, from whence I took the following : 

 The ancient Roman foot, = 11,635 Englifli inches. 

 The modern Roman palm, = 8,8i ditto. 

 The ancient Greek foot, = 12,09 ditto. 



The 



