E187 =4 
error of three fub-divifions may be 
committed. 
V. The fifth error may depend 
on the difference of time between 
the letting up each meafure and 
examining the column. From this 
head a difference of 10 fub-divifi- 
ons may enfue, 
VI. The fixth may be in deter- 
mining inaccurately the length of 
the column of air in the tube, 
which may seacumenes p to ae ome 
vifions. nae 
Vl. The feventh error may ae 
pend on the tube being kept in a 
direction more or lefS perpendicular, 
which may amount to three fub- 
divifions. All thofe errors refulting 
from the great tube make together 
35, and amount, in the three mea= 
fures of nitrous air let up in- one 
M 4 experi- 
