( 179 ) 
Now, in Oppofition to this Table, wherein the 
Heights mull needs, upon firft View, appear romantick 
and unnatural, let us confider the Height of fuch Moun- 
tains, as have been meafured,either by Trigonometrical 
or Barometrical Obfervations. 
In England, the Height of Snow don-hill, one of 
the higheft Mountains in IV ales, was meafured Trigo- 
nometrically, by Mr. J. Cafwell of Oxford , and found 
to be of 1240 Yards, or 3710 Englijh Feet, which 
make 3 48 8 Tar is Feet. At the Top of this Mountain, 
the Mercury fubfided to f 6 ,lt , which being redu- 
ced to Tar is Meafure, make juft 2 4". Now in the 
Tables above, the Height of the Place where the Mer- 
cury fubfides to 24 is, according to Mariotte , of 5*44 
Toifes, two Foot, or 3266 Foot above the Level of the 
Sea, according to ‘Caffini, 676 Toifes, or 40 <7 6 Feet, 
and according to my YJncle’s Calculation 5*59° 2*, or 
335^, fo that Mariotte comes 222 Feet fhort of its 
Height, as it was determined Trigonometrically, 
. Dr. Scheuchzer but 132', but Caffini exceeds this 
Height by 568 Feet, which confirms again, as I have 
ftiewn in a former Paper, that the Mariottian Table is 
preferable to that of Caffini, though pretended to have 
been corrected upon the former, and that that of Dr. 
Scheuchzer is an Improvement upon both. According to 
the Obfervation made by Dr, Halley, May 26, 1 697* the 
Mercury flood at- the Top of. Snow den-hill, at 2 6" 
\ f,f Englijh , which, if reduced as above, would give 
the Height of the Mountain fomsthing lefs. 
In France , when the Meridian Line 5 firft begun in 
1669, was continued in 1703, the Heights of feveral 
Mountains, particularly in the South of France, were 
determined Trigonometrically by the Members of the 
H h h h z Royal 
