( 4*4 ) 
not very obvious, but demonftrated from P rop. 5’. Lib. F. 
Theodofii Sphartc. For by it all Lines ered on the Surface 
pafs through the Center, where meeting with thofe 
from the Eye, they form the Plains of Vertical Circles 
thereto. And by the Converfe hereof it is evident, that 
this luminous Matter arofe nearly perpendicular to the 
Earth’s Surface, becaule it appeared in. this ered Pofition. 
And whereas in this Appearance (and perhaps in all others 
of the Kind) thofe Beams which arofe near the Eaft and 
Weft, as L, M , tf, were furtheft from the Perpendicular, 
on both fides inclining towards the South, whilft thofe in 
the North were diredly upright : the caufe thereof may 
well be explained by the Obliquity of the Magnetical 
Curves, making (till obtufer Angles with the Meridians 
cf the Terrella, as they are further from its Poles 
Hence alfo it is manifeft how that wonderful Corona. 
that was feen to the Southwards of the Vertex , in the 
Beginning of the Night, and fo very remarkable for it’s 
tremulous and vibrating Light, was produced ; to wir, 
by theConcourfe of many of thofe Beams arifing very 
high out of the circumjacent Regions, and meeting near 
the Zenith .• the Effluvia whereof they confided mixing 
and interfering one with another, and thereby occafion- 
ing a much ftronger but uncertain wavering Light. And 
fince it is agreed by all our Accounts that this Corona was 
tinged with various Colours, ’tis more than probable 
that thefe Vapours werecarried up tofuch a Height, as to 
emerge out of the Shadow of the Earth, and to beilluftra- 
ted by the dired Beams ofthe Sun .* whence it might come 
to pals that this firft Corona was feen coloured and much 
brighter than what appeared afterwards in (ome Places, 
where the Sight thereof was more than once repeated, 
after the Sun was gone down much lower under the Ho- 
rizon. Hence alfo it will be eafily underftood that this 
Corona was not one and the fame in all Places, but was 
