172 CAPTAIN A. E. CLAEKE ON THE COMPAEISON OF ENGLISH AND FOEEIGN 
The resulting value of F from 900 micrometer and 180 thermometer readings, extending 
over twelve days, is 
F=p- 55 -0-36+0-0066(*-62), (1) 
the probable error, when £=62°, being + 0T08. The unit to which these small quantities 
are referred is the millionth of a yard. 
The inch lines upon the foot are marked a , b, c , d, e,f, g, h, k, l , m, n,p ; the inch [ a . b~\ 
is divided into tenths by lines marked 1, 2, 3, 4, 5, 6, 7, 8, 9 ; the spaces [2 . 3], [6 . 7] 
are subdivided into hundredths; one of the subdividing lines in [2 . 3], called the toise- 
line, is indicated by the letter r ; the metre-line in [6 . 7] is known by the letter p. The 
values of the different spaces, as derived from 8000 micrometer readings, are as follows : — 
[«.2]= *^+3-71 + -063, 
[a.r]=^ o A + 5-30 + -109, 
[a . 3]= ^-0-20+'064, 
[«.4]=*p 2 -0-77+-066, 
[a.6]=-A^+S-00±-068, 
[ a . ft ]=J^,^ + 2-08+-086, 
[«.7]=* ^+1-58+ -068. 
[«.8]=*J+l-65±-070, 
[«.»]= ^+0-14+ -037, 
[«.e]= 2^ + l-74+-047, 
\_a.i\- 3^+l-31 + -038, • 
[«.«]= 4^+0-84+-051, 
[«./]= 5L+2-20+-047, 
[«•?]= 6^-0-87+-037. 
( 2 ) 
Ten-feet Standards . — The length of the 10-foot bar OI, was obtained by comparing 
each of the yard spaces on its surface, [a . 5], [ b . e], [c ._/*], [f. g~\, with Y 55 , and the two 
12-inch spaces \b . c], [e .f~\ with the foot F. The results are, at 62°, 
[a.b]= Y 55 +54-75+0-130, 
P ./]=|Y 55 -23-44±0-219, 
U-9~\= Y 55 — 10-23+ 0T56, 
whence the whole length of the bar, by adding these equations is 
OI 1 =J^Y„ + 21-08±0-299 (3) 
The length of the Indian steel standard, obtained in nearly the same manner, is 
I s =- 3 -Y 55 + 70-62+0-250 (4) 
Comparisons have also been made .between the following 10-foot bars; 0„ OI,, I B , I s , 
and I 4 . (This last is the old Indian Standard B, of which the comparisons between it 
and O, in 1831 and 1846 are detailed in the “ Account of the Measurement of the Lough 
