Jor the mercurial Thermometer. 53 
of prefixing the negative sign in our meteorological observations ; of 
which there would not be the least occasion, if the scale heparin 
ly adjusted. | 
Reaumur has placed the zero of his scale at the point, at which 
water just begins to freeze ;_ which is equal to 32° of Fahrenheit’s 
scale. This appears more natural and philosophical indeed than Fah- 
renheit’s ; because the point, at which water freezes, is a fixed point, 
and easily and certainly determinable ; but is at the same time much 
more inconvenient than his, as it is necessary to affix the sign + or — 
to every degree noted down ; which is not only troublesome in itself, 
but is a constant source of error. For. if the sign happen to be omit- 
ted, when the degree to be noted is within a few, either above or be- 
‘low zero, the notation is quite uncertain, and the error may be great. 
But if the wrong sign be prefixed, it must be great. Nor is this all ; 
._ the degrees on Reaumur’s scale, which are each equal to 2} of Fah- 
renbeil! s, are by much too large. Too large even for the common 
eteorological observations, which are far from. requiring 
reates! ian accuracy. It would certainly be thought too 
vague an expression to say, €. gr. + 15, or —16°, when the mercury 
stands by 8 scale in the interval between those two degrees. And if. 
the exp were conveyed in fractions (which is still increasing the 
trouble), the parts of a degree must be estimated by the eye, which 
seems too inaccurate a indie of determining: ; — when more 
precision may be obtained by an easier one. 
Of these two thermometers then, there cannot be ‘ineAtictaice 
with ee this country, which to prefer ; Reaumur’s being so 
very incomme dious for the reasons just mentioned. But Fahrenheit’s, 
though more convenient, is certainly imperfect and needs alteration. 
_ Iam fully sensible of the great inconvenience there is in intro- 
ducing a new standard. So many observations have been made on 
