[ 206 ]’ 
now and then ftroking the cord betwixt the thumb 
and finger downwards, in order to> lay the fibres 
thereof clofe together, and thereby caufing it to 
lengthen as much as poffible : when the index is 
thus become ftafionary, which will generally hap- 
pen in about an hour (more or lefs as the air is 
naturally more or lefs dry), by means of the peg 
at top raife or deprefs the index, till it lays over 
the point o ; this done, remove the inftrument from 
the fire, and having ready fome warm water in a 
teacup, take a ‘ middling camel’s hair pencil ; and 
dipping it in the water, gently anomt the cord, till 
it will drink up no more, and till the index becomes 
flationary, and water will no more have effedl upon 
it } which will alfo generally happen in about an 
hour. If in this date the index lays over the de- 
gree marked loo, all is right; if not, flack the 
Icrew S, and Aide the fcale nearer to or further from 
the center, till the point loo comes under the in- 
dex, and then the inftrument is adjufted for ufe : 
but, if the compafs of the Aide is not fufheient to 
efteft this, as may pro^bly happen on the Arft 
adjuftment, Aack the proper ferews, and move the 
Aiding ftudd I nearer to or further from the center 
of the index, according as the angle formed by the 
index, between the points of dry and wet, happeneth 
to be too fmall or too large for the fcale ; the quan- 
tity can eafily be judged of, fo as the next time 
to come within the compafs of the Aide of the 
fcale j the quantity of Aide being 4 of ^he length of 
the index, and confequently its compafs of adjuft- 
ment of the whole variable quantity. Now as 
ffiding the ftudd I will vary the polition of the in- 
7 
4 
