7 6 Captain Kater on the comparison of 
inches from each other, were laid off on a large plank from 
General Roy’s scale, the whole length being 20 feet ; and 
by means of this plank the length of the glass rods was 
determined, with which the base on Hounslow Heath was 
measured. 
In the Philosophical Transactions for 17 95, it is stated, that 
Mt.Ramsden compared his brass standard with that belonging 
to the Royal Society, after they had remained together about 
24 hours, when “ they were found to be precisely of the same 
“ length.” Brass points were then inserted in the upper 
surface of a cast iron triangular bar of 21 feet in length, from 
Mr. Ramsden’s standard, at the distance of 40 inches from 
each other, the whole length of 20 feet being laid off on those 
points in the temperature of 54 0 . 
By means of this bar, the length of the hundred feet steel 
chain was determined with which the base on Hounslow Heath 
was re-measured, and was found to be only about 2^ inches 
greater than the measurement with the glass rods. 
The standard scale used by Mr. RAMSDEN'in laying off the 
points on the iron bar, is, it seems, no longer to be found ; but 
from the declared equality of both this and General Roy's 
standard with that of the Royal Society, and the near agree- 
ment of the two separate measurements of the base with the 
glass rods and with the steel chain, one might have been 
tempted to consider General Roy’s scale as precisely similar 
to Mr. Ramsden’s, and as offering the best source from 
which the national standard yard might be obtained. 
The spirit however, of the recommendation of the Com- 
missioners of Weights and Measures, appearing to be, that 
the standard yard should be derived from the base of the 
