CD is the Alr-TIiermometer; tlie fara& 
-ip^nneiv, with ^^^^ ^^Sr^^^^;/.- 
EF is a Plate applycd ,td elk" fide of the Thertnorneter 
CD> graduated into fpaces anfvyerin^ to. inches and 
.parj^f qf aniach of Mercury;, in the;C;oitimdri'BarcmeteB. 
C^i a-^jbjan^^^ ftandiqg pK^^ V^^ti aFVhe h<^i^t of *tfo 
^ercuty ■ thereon,^ as^ It' w^3^}^iieh'. tti£ IiiftruiAent 
^graduated, as ffippofe'h'efe'at'^c)'^^ ' ■ 'iji; -^ - 
LM a Wire on which thePl^te EF flips iip; ail (fdbv^^^ 
patallel to. the ,Cj:afle of the Therrppmetcr C D^ ^^^'}^^^ 
: axff point at whicK'tlfc arthe'time of 
obrervation 5 fuppofe at 38 Oil rheSpirit-TliSnitdn^eter • 
aidie the Plate :E:F fiU the |iand G ftiM' at ^58 'dn the 
Air^Thermornetcrj and if the Liquor therein ftand at ^8. 
Jikewife, tlifn is the prefibre of the Air the faiire as at 
the time oi Graduation 5^ viz. 2 9; 5^3 but 'if it'ftand 
l^igher^sat 50 at I,theh is thfe^preflbre 
4nd tiie divifion on th^ flidipi^ PJiV^'a^^ the tiquof, 
ftewsthe prefi^ntheigK^ oif :the^^9ipr'i^^ 
'tenths. And this may'fufHcras to'tft^ ffiaftner of uf^iig 5t 
I had one of thefe Barometers vyith-^me m my Tate 
Southern Voyage;, and it never failed to 'progqofVick ^nd 
give early notice pf ^11 the bad. Weather we had;^fd ttiat 
I depended therpon, . and^rnade j^oyiffo 
and from my owri experience I conclude that a more ufcr 
ful contrivance harh not for this long tiraejbeen offered 
for the benefit of Navigation.^ ^ / ^^^f^?"^^ 
- Thefe Inftruments . are made kcordife W -^tlle:' d i; 
reftion of Dp Haok^ By .. Mr ' Henry ^ If tm^ OpQ^^^ 
Royal Society, v\^ho will furhj(li\any'C;t'dtIeman with 
them, and give them direftioris h6w to' ui^e them. 
Printed fox Sam. Smith and Bcnj. Walfird^ Printers to the 
Royal Society,^ a-t? the Princes Arms in St. Paul} 
Church-yard. ijoi- 
