thing, but inclined to the Plan of the Horizon at a certain an- 
gle being near an half right one 5 to which were particularly 
appropriated thofe Cylinders, which M. Des Cartes faw fall from 
the Heavens , having Stars at both ends : As may be feen ex- 
perimentally , by forming Cylinders of that fafliion, which is 
reprefented VII, and letting them defcendinthe Air 
or in Water. That in thefe Cylinders was found, following 
the Cdcdus to be given in the Trcatife of Parhelia s , not on- 
ly the Caofe of the Anthelia made by the interfedlion of two 
Arches, asinF/f, VIH, but alfo that of fome other Extraor- 
dinary Arches and Rods , that are fometimcs obferved near the 
Sun , of which notwithftanding there could nothing beasyet 
affirmed with certainty^for want of exa(aand faithful Obferva- 
nons* 
To make all thefe d fferent effedlsof the Cylinders manifeft 
to the Eye, M. Hugens produced one of Glafs, a foot long, 
of thefiiape of that in Fig. IV 5 and for the kernel opaque 
in the middle , a Cylinder of Wood 5 and the ambient fpace 
filled with water , inftead of tranfparent Ice: Which Cylinder 
being expofed to the Sun , and the Eye put in fuch places as 
wasrequifit, there were fucceffively feen all thofe reflexions 
2nd refractions, that have been difcourfed of. Whence it 
might be concluded, that a great number of the like Cy linders, 
although very fmall in comparifon to that , being found in the 
Air , and having the feveral poftures that have been fuppofed, 
all the Appearances of the Parhelia and their Circles muft ex- 
adly follow. 
It jVas wiihed , for an entire confirmation of the truth of this 
Hypothefis , that fome of thofe fmal Cylinders could be ob- 
ferved to fall to the ground at the time , when any Parhelia do 
appear: Which he fliowed could not eafilybedone^ becaufe 
that the vapors , which then rife from the Earth upwards , and 
which are the caufe of their Cylindrical'figurej keep themalfo 
fufpended in the Air. He added^ that it was not to be thought 
ftrange, that fuch fmallgrains of hail were thus kept up in the 
Air by the vapors, forafmuch as thefe, by being rarify ed and di- 
lated upwards^ might have motion|enough for this effe<5l. rhat 
that was more eaiy to conceivCj than to imagine, how thefe fame 
N i vapors 
