estimated in Parts of the English Standard. 433 
Comparison of the Metre a traits. 
Distance in inches 
S [deg [22 |=2elea0tel zeal 
2 |aesa Be od s&sl\U 8255 aise between the lines 
E ee Ee < i % £ Qe 3S 22 bina s Be @ BA| designating the 
2 esl slSey | oSa(s 2552) & 2 Ys) méive, the metre 
= ger se S222 2 2 on Rese being at. 32°, and 
& BAe 23 BEE POT ED DES") Geico oon 
60:0 | 83-0 | 644-5] 559-5] 39°37606 | "00664 39 8701 2 
60-7 | 75-5 | €39-0| 563-5} $9°37588} "00589 | 39°S6999 
61-7} 69:2 | 634-0] 564-8] 59-37583| C0568 | 39°37015 
62:0 | 65:0 | 680°5| 565 5] 39°57580 | *00562 59°S7018 
62-4 | 61-0 | 629-0] 568-0} 39°37569 | -00554 39'S37015 
62°53 | 58-7 | 629-5] 570°8 | 39-37557 | *00556 39°57001 
62°2 | 58-0 | 628-0] 570-0! 39°37560| ‘00558 | S9°57002 
62°2 59.0 625-0] 566:0] 39°37577 | *00558 39-57019 
62+] 59°0 625°5| 566-5 | $9:37575 | *G0560 39 37015 
588 | 900 | 638-0] 548-0) G9:37654 | :00629 29-37025 
59-0 83°0 657°0] 554:0} S9°37629 | *00625 59°37 4 
590 82:0 6360) 554:0 | 39°37629 | 00625 | 59°37004 
59*2 5:2 632-)} 548 §| 59°37651] “00621 | 39.57030 | 
59-1 81:0 632.0 | 551°0| $9°37642 00623 39 37019 
Mean SOSTOL2 
The distance between the lines designating the 
métre was found by M. Arago to be too sie} -+000'69 
by a quantity =:00069 of an ineh, which add 
The distance from zero to 39-4 of Sir G. Shuck- 
burgh’s scale is too short compared with the — 00003 
mean of its divisions by ‘00005 of an inch,which 
Serb inacictt: w seu ache vita: felassacie tee © melas 
Hence the length of the métre in inches of Sir G. t 6937076 
Shackburgh’s seale is... 2. --- ee eee oe a! 
The comparison of the metre @ bouts presented considerable 
difficulties, which I conceive it would be of little use to detail, as 
the necessity of comparisons of this kind is of very rare occur- 
rence; I shall therefore proceed to describe the method which 
was at last found successful. 
Four rectangular pieces of brass were prepared precisely si- 
milar to those described in the account of experiments on the 
pendulum in the Philosophical Transactions before referred to. 
These were marked C, c, D and d. ‘The perfectly plane rect- 
angular edges of the pieces C and c, being placed in contact, 
and kept thus by means of a spring, the distance of the fine lines 
drawn on their surfaces, parallel and very near to the rectangular 
edges, was found to be 500°5 divisions of the micrometer ; and the 
pieces D and d being placed in like manner in contact, the di- 
stance of the lines on their surfaces estimated in the same divi- 
sions was 456°7. 
The métre a bouts being placed by the side of the brass scale 
and in contact with it, the pieces D and-d were applied to its 
extremities, the surfaces of the brass pieces being a little below 
the surface of the métre in order to preclude any error which 
* See page 176. ‘ 
Vol, 52, No, 248, Dec. 1818. Ee might 
