new standards of weights and measures. 41 
To determine this distance I employed the following 
method : 
Two bars of brass were prepared, three quarters of an inch 
square and rather less than 18 inches long. They were ter- 
minated by planes at right angles to their length ; and upon 
the upper face of each bar, very near to the end, a fine trans- 
verse line was drawn ; the other ends of the bars being then 
placed in contact and kept so by springs, the distance between 
the lines was taken by means of two micrometer microscopes 
fixed to a bar of wood and referred to Sir G. Shuckburgh's 
standard scale, which scale, it has already been remarked, 
does not sensibly differ from the imperial standard yard. 
The distance between the lines was found by numerous 
comparisons to be 919 divisions of the micrometer less than 
the standard yard, each division of the micrometer being 
equal to — l ~r of an inch. 
The brass bars were then placed upon the standard to be 
examined, their marked ends being next each other, and 
their opposite extremities kept in contact with the steel faces 
by a spring introduced between the bars, a part below the 
surface being cut away for that purpose. The distance 
between the lines was then measured by the micrometer 
microscope, which distance, had the standard been perfectly 
correct, would have been equal to what the distance of the 
lines in the former position of the bars wanted of 36 inches. 
Standard Yard, No. 1. 
The distance between the lines upon the brass bars was 
found by the mean of six measurements to be 918,2 divisions 
of the micrometer, which differs so little from 919 divisions, 
G 
MDCCCXXVI. 
