f 224 ] 
§>lane country in the neighbourhood of London. 
It may, therefore, be proper for the London work- 
men to fix their boiling point, when the barometer is 
at 30 inches. Fahrenheit’s divifion of the fcale, 
which makes 1 80 decrees between melting ice and 
boiling water, and places the point of o at the 
3 2d degree below melting ice, may be retained; 
foecaufe long ufe hath rendered it familiar to us. 
A thermometer thus conftrudted, I fhall call bird’s 
.Fahrenheit : that eminent mechanic, our coun- 
tryman, Mr. John bird, having been, as I be- 
lieve, the firfl workman, who took the pains to 
attend to the ftate of the barometer, in making 
thermometers, and having always made it his prac- 
tice, to fix the boiling point, when his barometer 
hath flood at 30 inches. Taking it for granted, 
that this fcale will continue in general ufe here, I 
fhall give an accurate companion of it with the 
fcale of M. de luc. 
T being put for the height of a thermometer 
plunged in boiling water, above melting ice, in 
hundredths of a degree of M. de lug's fcale, in 
any given ftate of the barometer ; let 0 denote the 
fame height, in hundredths of a degree of bird’s 
Fahrenheit. 
Put)' for the height of the barometer in i6ths of a Paris line. 
v for its height in Paris lines. 
x in lOths of a Paris ineh. 
~ in ioths of an Englilli inch. 
And for 10387 put a . 
for 16 put b. 
for 10 put c. 
for 1 2 put d . 
Alfo put E and F for numbers exprefiing the pro- 
portion of the Englifh foot to the French foot. 
Now 
