• / 
I 45 4 ] 
F. 
The force of it can only be juftly afcertained by its effeft on fome known body, 
p. -07. Method of producing diftin£l colours and lhades from calces of iron com- 
pounded with clay by different degrees of fire, ibid. The Cornifh porcelain clays 
belt for fupporting the intenfity and meafuring the degrees of fire, p. 309. Method 
of preparing them for thermometric purpofes, ibid. 
t Fitzgerald, Keene. His experiments with Chinefe hemp feed. See Hemp Seed. 
Fitzgerald, Mr. * See Thermometer . 
o 
Fixed air, or the aerial acid. Is capable of exiftirig in two dates, p. :g$. Cannot be 
feparated from any fubftance in a concrete date, and why,, p. 196. See Elrffricity, 
Saline SubJlanceSy -Sulphur. 
Fixed Jlars. On the parallax of, by Mr. Herfchel, p. 82. Difficulty of afeertaining 
the dillance of the fixed liars, and from what caufes, p. 82. See Angles. The noble 
method pointed out by Galileo, and firlt attempted by Hook, Flamftead, Molineux, 
and Bradley, of taking ditlances of liars from the zenith that pafs very near it, 
though it failed with regard to parallax, has been produdlive of the mod noble difeo- 
Teries of another nature, p. 84. Remarks upon Bradley’s method of finding the 
parallax, p. 85, 86. De la Lande concludes that the queltion about parallax is 
refolved, and why, p. 84. Difficulties attending the method of zenith dillances, p. 
86. The method taken by Mr. Herfchel to find the parallax, p. 87. See Telefcvpes. 
Which is free from every error the former is liable to, and by which the annual 
parallax, if it fhould not exceed the tenth part of a fecond, may dill become vilible, 
and be afcertained at lead to a much greater degree of approximation than it ever has 
been done, p. 89. et feq. See Optics. High powers of magnifying abfolutely necef- 
fary in the refearch of the parallax of the fixed dars, p. 93. Two different ways ufed 
by Mr. Herfchel in fettling the dillances of double dars, p. 99. With his method of 
claffing them, p. 100. et feq. General podulata refpefling the theory of the annual 
parallax of double dars, &c. p. 104. et i'eq. General obfervation on the time and 
place where the maxima of parallax will happen, p. in. 
f-lamjlead. See Fixed Stars. 
G. 
Gahleo. See Fixed Stars. 
Gioeni, Count de. See Rain. 
Gcr/ut by William. His regider of theParifh of Holy-Crofs, See Holy Crofs, 
Hamilton t 
