( *45: ) 
tion of this Appearance in general, and then defcends 
to a Detail of the feveral Particulars, adding the So- 
lution of each. The next Seftion is employed in re- 
lating the Hiftorical Proofs of his Hypothefis con- 
cerning the Northern Lights , taken from the Records 
we have of feveral Appearances of thofe Lights, to 
be met with in ancient Authors, compared with thofe 
of the Zodiacal Light, their fuppofed Caufe, and the 
Situation of the Earth in her annual Orbit at thofe 
times. The lad Seflrion confifls of twenty-eight cu- 
rious Queftions concerning feveral other Phenome- 
na of Nature, which the ingenious Theorift believes 
to have a Dependance upon his new Hypothefis, and 
explicable by it. 
But a more particular Account of thefe Matters 
may juftly be expe&ed. 
Mr. Mairan begins the whole with laying before 
the Reader a fhort View of his Hypothefis concerning 
the Nature of an Aurora Borealis, defining his Terms 
as he goes along. 
The Aurora Borealis, fays he, is a luminous Phe- 
nomenon , fo called from the Place of its Appearance, 
ufually in the Northern Parts of the Heavens,, and. 
with a Light near the Horizon, refembling that of 
the Morning Dawn. This Name is fuppofed to be 
firft given it by Mr. GaJJendiy but it appears other- 
wife, from a Place in his Animadverfions oa Dioge- 
nes , quoted by Mr. Mairan. 
The Caufe of an Aurora Borealis, in genera], he 
takes to be a Light called the Zodiacal Light,, which 
is in reality nothing elfe but the Atmofphere of the 
Sun fpread on each Side of him along the Zodiack ? 
in the Form of a Pyramid. This fometimes is ex- 
tended, 
