( * 4 * ) 
tended to fuch a Length as to reach beyond the annu- 
al Orbit of our Earth, ,and in thefe Circumftances 
fometimes to blend itfelf with our Atmofphere, and 
being of an Heterogeneous Nature, produces the fe- 
verai Appearances which are obferved in, and ufu- 
ally cotnpofe the Northern Lights. This he un- 
dertakes to explain, and prove more largely, in the 
fequel of the Work. 
A Difcourfe upon the Nature of the Zodiacal 
Light , or Sun’s Atmofphere, and the Matter of 
which it confiifs, is the Subjeft of the third Chap- 
ter. That it is very different from the Ambient 
./Ether, he fays is evident, in that the /Ether reflects 
none of the Light of the Sun, is extremely rare, and 
altogether imperceptible. Whether the Zodiacal 
Light of the Solar Atmofphere be any Emanation from 
the Body of the Sun, a Species of Effervefcence, or 
Depuration of its groffer Parts, an Amafs of Hetero- 
geneous Parts diffufed in the /'Ether, that meeting 
from all Parts, tend towards the Sun, & c. he will 
not undertake to determine. 
It is enough for his Purpofe, that it is of a lumi- 
nous Nature, whether in itfelf, or becaufe ftrongly 
illuminated by the Rays of the Sun, whofe Body it 
environs. He does not deny but that it may be alfo of 
an inflammable Nature, nay" adtual Flame or Fire, 
though very fine and rare. 
He obferves, that the Form in which the Atmof- 
phere of the Sun is commonly feen in total Eclipfes 
of the Sun, is Round, though fometimes Conical, of 
which he gives us a Figure. 
At all other times it moil ufually prefents itfelf to 
us inthe Form of a lucid Pyramid, or Lance, lying 
oblique _ 
