C 691 ] 
As the Divifions pointed out by the Index will be 
different with Rods of different Metals or Subftances, 
you may make different Circles upon the Plate for 
the Range of the different Rods, and mark them 5 
the Iron Rod, the Brafs Rod, the Clay Rod $ and 
fet the feveral Marks above fpecified upon each Cir- 
cle apart j or you may, to avoid Confufion, have a 
different Inftrument for each kind of Rod. 
Being obliged to take down my Athanor and 
Wind-Furnace, upon removing twice to different 
Houfes, and not having rebuilt them where I now 
live, I have not had Opportunities yet of fixing the 
Scale of my own Inftrument, which was one Rea- 
fon why I did not publifh an Account of my Inven- 
tion fooneri for I hope hereafter to be able to com- 
pare the Degrees of Heat neceffary for the melting 
of each Metal, and to determine the Queftion whe- 
ther Metals in the higheft Degree of Fulion are fuf- 
ceptible of greater Degrees of Heat by increafing the 
Fire, as Water thoroughly boiling can never Ibe 
made hotter j nor did I intend to have publifh d 
any Defcription of this Inftrument till I had com- 
pleted Tables of the Degrees of Cold and Heat, from 
Fahrenheit's Experiment of Cold produced by Art 
40 Degrees below o to the Heat of melting Iron. 
According to Fahrenheit's Scale, the Heat of the 
ftrongeft Sunfhine is at about 80. Spirit of Wine 
boils at 1 76. Water at 212. the Lixivium of' Salt 
of Tartar at 240. Spirit of Nitre at 242. Oil of Vitriol 
at 546. Quickfilver at 600 *. 
As 
* See Auguftin. Grifchow Thermometria co?nparata accuratiu$ y & Har* 
monica. Berolini 1740, 4^ p, 10, 
