304 PHILOSOPHICAL TRANSACTIONS. fANNO 17g8. 



may be fitly considered as the standards of this kingdom ; and herein a small dis- 

 crepancy between themselves, in these authoritative standards, will have no influ- 

 ence on the general conclusion I propose to draw; which is, not so much to say 

 what has been the standard of Great Britain, as what it shall be henceforward, and 

 may be immutably so; and which shall differ but a very small quantity, and that 

 an assignable one, from those that have been in use for 2 or 300 years past. Bv 

 these means, no inconvenience would be produced from change of terms, or sub- 

 divisions of parts, or from sensible deviation from ancient practice: all that will be 

 done, will be to render that certain and permanent, which has hitherto been fluc- 

 tuating, or liable to fluctuation. To give effect and energy to these suggestions, 

 is the province of another power. 



The chief standards of longitudinal measure, are those preserved in the Exche- 

 quer; in the House of Commons; at the r. s.; and in the Tower. The first 

 alone indeed bear legal authority, and have been in use for more than 200 years; 

 the last is considered as a copy of them, and is not used for sizing generally. The 

 other two are of modern date ; and though they do not carry with them at present 

 any statuteable authority, yet from the high reputation and acknowledged care of 

 the artists who made them, the celebrated Mr. George Graham, and Mr. John 

 Bird, they are doubtless entitled to very great respect; and are probably derived 

 from a mean result of the comparisons of the old and discordant ones in the Ex- 

 chequer. I shall begin with that of Mr. Graham, which contains also the length 

 of the Tower standard laid down on it ; will proceed then to Mr. Bird's, and 

 finally conclude with those at the Exchequer. 



May 5, 1797, I went to the apartments of the r. s., at Somerset-House, and 

 made the following observations on Mr. Graham's* brass standard yard, made in 

 1742. This scale is about 42 inches long, and half an inch wide, containing 3 

 parallel lines engraven on it, on the exterior and ulterior of which are 3 divisions, 

 expressing feet ; with the letter e at the last division, and, by a memorandum, 

 preserved with it in the archives of the Society, is said to signify English measure, 

 as taken from the standard in the Tower of London. That with the letter f 

 denoting the length of the half of the French toise ; put on here, by the authority 

 and under the inspection of the Royal Academy of Sciences, then subsisting at 

 Paris, to whom it was sent in 1 742, for the purpose of comparing the French and 

 English measures. The middle line, marked Exch. of the three above-mentioned, 

 denotes, as is supposed, the standard yard from the Exchequer. 



This bar had been previously laid together with my scale divided by Mr. Trough- 

 ton, for 24 hours, to acquire the same temperature; they were also of the same 

 metal, and, by placing it under my microscopes, adjusted to the interval between 

 10 and 46 inches, I found the interval on the Tower standard exceed mine, by 



* This rod was not made by Mr. Graham, but, at his instance, procured by him from Mr. Jonathan 

 Sisson, a celebrated artist of that time. See Phil. Trans., rol. 12. — Orig. 



