32S 
F %rious Notices^ 
coals are apt to coak together, and admit no more air through them,, 
than they can decompose : besides which, the smoke of the coal 
greatly tends to decompose the current of air which passes imme- 
diately under the lowest plate. Coal, therefore, is the best fuel 
for the purpose ; that is, the coal that smokes and flames, while it 
burns. 
But, if the rollers be well greased while the iron is passing 
through them, which they ought to be, the scales separate, the 
surface becomes smooth, and a fine bluish colour can be after- 
v/ard given by proper annealing, if it be necessary to please the 
eyesight. 
While I am upon the subject of iron, I feel much inclined to 
regret that the Ordnance with which our Navy is supplied, is not 
better than I hear it is. I do not know the fact, but lam told, that 
had the guns on board Commodore Rogers’s ship been good, he 
■would have taken the Little Belt : and that Commodore Chauncey 
was nearly killed by the bursting of a cannon ; an accident that hap- 
pens so frequently on board our vessels of war, as to become an 
evil of great magnitude. About a month ago a general officer in 
our regular army, told me, that he had seen a lump of lead about 
five pounds weight taken out of a cannon ; the lead had been run 
in to conceal a defect in the casting. If this be the case, some 
remedy should be applied. 
In England, spring-chains of iron have been substituted instead 
of Cables. In 1812 three ships of the line were thus fitted up; 
whether the improvement, if it be one, is continued, I know not. 
Thermometers. — The following formulae for the conversion of 
the degrees of the various Thermometers that are in use in this 
country, in England, and the continent of Europe, into each other, 
will be found useful to a chemical and philosophical student. 
To convert the degrees of Reamur’s into those of Fahrenheit’s. 
fiy£j-32=F. 2d. To convert those of Fahrenheit into Reamur’s.^ 
4 ^ 
3d. To convert Celsius’s into Fah. ~ ^^4-32=F. 
9 5 
32 ^ 
4th. To convert Fahrenheit’s into Celsius’s. — -= C. 5th. To 
convert Celsius’s degrees into Reamur’s.£2il=-?R. 6th. To con-' 
R X 5 
vert Rcamur’s into Celsius’s. — = C. 
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