'Major-General Roy’s Account of the 
quantity of the melted metal on the irons, made ufe of for 
•drawing them at the glafs- houfe. 
The week of rainy weather, which ended the month of 
July, occafioning, as has been faid, a total fufpenfion , of the 
operations on the heath, was employed in procuring a fuffi- 
cient number of glafs tubes (one whereof was not lefs than 
twenty -fix feet long) and regulating with Mr. Ramsden 
every thing concerning their conftruftion into meafuring rods. 
The deicription of them we (hall however defer until the time 
of their application in the field, after having finilhed the opera- 
tion with thole of deal. 
On Monday the 2d of Auguft, the operations on the heath 
were refumed at 8 h. 30' A.M. by comparing the rods with 
the ftandard, which they were found to exceed by one-fortieth 
of an inch, the temperature then being 66°. The forward 
ond of the rod now placed over the tripod at N° 27, com- 
pleting the 800th length, reckoned from the lower end of 
the bafe by rods of 243 inches each ; and thefe being equal 
to 810 rods of 240 inches; it w T as judged proper to mark a 
point upon the ground correfponding to this forward end, that 
it might be referred to in returning back with the meafurement 
by the glafs rods. This was done by finking two fmall pickets 
into the ground, about a foot afunder, one on each fide of the 
bafe, and at right angles to it. A filk thread being then 
Rretched over the tops of the pickets, and gently moved on 
till it touched the filver wire fufpended from the end of the 
rod, fine notches were then made with a pen-knife in the tops 
of the pickets, whereby the thread could be replaced in the 
fame fituation ; which being done, the pickets were covered over 
with earth. In the courfe of this day nine hypothenufes were 
meafured 5 and at 7 h. P.M. the tripod was placed at the thirty- 
fixth 
