(iC7o) 
rated by thefe perpendicular Cylinders , and fo difpofed itt the 
great white Circle, that the Spedator , turning his face towards 
the true Sun , hath them behind him 3 as in the Roman Obfer- 
vation arc the Parhelia L and M. 1 hat thefe arc produced 
by two rcfradtions and one reflexion in thefe Cylinders, in the 
fame manner as the ordinary Rain-bow in the drops of water , 
according as M. Des-Cartes hath declared : So that the opaque 
kernels do nothing to the produft ion of thefe two Suns, but 
that they may be fometimes fo big, as to make them not ap- 
pear. 
r^S-^f according to the Altitude of the Sun, more orlefs, 
thefe two Parhelia zxt more or lefs nigh to one another 5 of 
which he promifeth to give the true meafures inhis Treatifeof 
Parhelia s. 
That th^y (hould appear coloured, as the Rainbow, and 
that fometimes they have been feenfuch> but that when they 
are faint , they may alfo feem white , even as the Halo\ when 
they are not very bright. 
That thefe fame perpendicular Cylinders can alfo produce 
an about the Sun, by reafonof the rounding of their two 
jends 5 which maketh, that being diftaat from the inn at a cer- 
tain angle, on what fide foevet it be, they begin Tom thence 
to give paflage to the rays , tranfmitting them to the Eyes ot 
the^peftator. And that thefe //<i/(? sare piobably thok, we 
fee almoft always pafs through the two Parhelia thit are on the 
fide of the true Sun , as the Halo G K N I in the Ph^enoimetion 
7^4^ there is yet an other fcruationor thefe Cylindeis very 
confiderable , which is of thofe that are couchant , fo as their 
Axes are parallel to the plan of the Horizon, but turn'd divers 
Iways , fome one fome another way , like needles confufedly 
thrown on the ground : Which Horizontal difpofition is very 
tiarural to thofe Cylindrick Bodies 5 fiipported by the vapors, 
which rife from the earth , as may be made out Experimental- 
ly in Bodies thitS; figur'd , being let foil in the Air, 
7 hat it is in thefe Cylinders, that the Arches ^ which touch 
the:.fir4^i?-s:above;orbelc»w , are formed 5 fuch as there were in 
xh^PhAnmetion obferv'd at Rome A. 16^0. which is defcri- 
bed 
