1 30 Gen. Roy’s Account of 
thoufand feet, a ftrong picket, which were numbered i, 2, 3, 
&c. from the pipe at High Nook to the 28th near Ruckinge. 
In all this preparatory part of the bufinefs he had no other 
affiftants than the artillery-men of his furveying party. But 
for the ultimate determination, it being abfolutely necelTary 
that he fhould have the aid of fome perfon in whom he could 
confide for the management of the operation in general, and 
particularly for the adjuftment of the fcale at one end of the 
chain, while he himfelf was adjufting that at the other ; there- 
fore Lieut. Bryce, of the Royal Artillery (now of the Corps 
of Royal Engineers), an attentive officer and excellent ma- 
thematician, was left with him for thofe effential purpofes. 
Thefe two gentlemen began the operation on the 15th of 
October, and, after experiencing many difficulties arifing from 
the badnefs of the weather in that late feafon of the year, and 
the defe&ivenefs of the apparatus, it was only by dint of great 
labour, and the utmoft perfeverance, that they were enabled to 
accomplifh the meafurement on the 4th of December fol- 
© 
The annexed general table of the bafe, which contains five 
columns, fhews the progrefs that was made in the work from 
day to day. The firft column contains the date ; the fecond, 
the fpaces meafured each day, reckoned by hundreds of yards, 
and denoted in the general plan by ftrong dots ; the third 
fhews the temperature of the chain deduced from the mean of 
fifteen thermometers, five for each chain ; the fourth expreffes 
the difference of temperature above or below 62° of Fahren- 
heit ; and the fifth fhews the correction anfwering to that 
difference, additive to the apparent length with the fign + , 
and fubtradive from it with the fign — . 
2 
lowing 
From 
