needful to preferve the material Syftem: 219 
cenxe.to the atmofphere in parallel lines, or in cylinders, whofe 
axes were diameter-lines of the expanfe, and whofe bafes were 
equal to thofe fegments, would pafs through the atmofphere 
to the.correfponding.fegments of the expanfe, and be reflected 
from them ; and afterwards, in the fame clafled ftate, unite in 
a ox. from which they would diverge, pe exhibit their fe- 
To give e Tome idea, though an unpedéd 6 one, i that focus, 
the reflection and.convergence may be conceived as made (fome- 
what in the manner above-reprefented) from the fegments com- 
pofing the whole furface of the expanfe : that each fegment 
would refle& a.cone of rays, terminating in a focus ; and that 
ithe united foci of thofe cones, which muft be confidered as 
«coming from all quarters of the expanfe, would conftitue its 
In fome fuh difpofition, and fate of things, as here repre- 
fented, it is conceivable, that the fyftem-light, tranfinitted to 
the-expanfe through its atmofphere, might be reflected from 
thofe fegments ; and. for the moft part converge in cones to- 
wards < a E! focus : where, -by means of the refraction and 
fe n; it had undergone in that tranfmiffion. and reflection, 
it a gs in each cone, arranged or claffed, according to 
the different-refrangibility and reflexibility of its rays., After 
the says had paft the boundary of their focus, they would in- 
teríe&. each. other, and. form: new and reverfed cones, Or conic 
Ddza ! figures»: 
"any extra-central dire&ion ; and that this may be-aflirmed of every two oppofite 
parts or fegments in the whole furface. of the expanfe. The effe& of the atmof- 
phere, in regard to the refraction, is not here noticed. Thefe rays, like’ the fun's 
rays at the earth, are confidered as. parallel, by reafon of the great. diftance of the 
radiant bodies, and the confequent extreme minutenefs of the angle of divergence 
at fuch a diftance. E 
