7 
Measurement of a Bafe on Hoiuiilpw-Heath. 4.2 9- 
tinned there fame time ; blit the weather becoming rather, 
worie, it was utterly impoffibie to fhew their Majefties the 
nature of the operation,, by any progrefs that could at that 
time be made in the work. 
After a continuance of unfavourable weather for federal days,., 
the operations were relumed at 9 h,. A.M. of the 23d, when the 
rods being compared were found (till to exceed the ftandard by 
one-thirtieth of an inch, and the temperature now was 6r°.. 
Here it is to, be ohferved, that in our, progrefs forward,, an accu- 
rate regifter had. been all along kept of that point of each rod 
correfponding to the center of the hypothenufal pickets, by 
noting its diftance from either end, whereby the error of the 
chain at each ftation was readily difcovered. at the fame time 
•/ * 
that the revolutions of the three rods fer.ved to keep the account 
of the total meafurement. In order, therefore,, that this me- 
thod might, be diftindtly adhered to, it was judged proper to 
pufh on the rod that lay over the tripod at N° 1 o. exactly forty- 
five inches, to make good the deficiency of the firft fifteen 
coincident rods, and that the account might be kept from the 
lower end of the bafe in entire rods of 243, and complete 
revolutions of 729 inches each. This being done, the reft 
were placed in the ordinary fucceflion and we finifhed the 
bufinefs of the day at the eighteenth ftation, where the rods 
being compared at 6 h. P.M. their mean length was found to 
exceed that of the ftandard A^th part of an inch,, the tempera- 
ture then being 54°, 
On Saturday the 24th of July, the rods were three times, 
compared; at 7 h. 30' A.M., 1 1 h. 15' A.M., and 5I1. 45' P.M. 
Their mean excefs above the ftandard was, found to be one- 
thirtieth of an inch, and the mean heat 64°, In the courfe of 
theiday, the measurement was continued from the eighteenth to 
the 
