( ) 
the Point E comes below I, and the Beam is wholly 
refradted; I ask whence comes the faint Image at k> If 
at be anfwered, that fome Part E I of the Line EF 
{ Fig. 19 ) is turned up to the Eye at E f Fit. 17 ) 
what becomes of the lateral Cohefion of Light on 
which Rtzzetti founds his chief Propofition, and 
iroin which he draws his Confequences ? 
It would be tedious as well as ufelefs to be particu- 
lar in mewing all Rizzettis Miftakes- therefore I 
ihall only mention one more Experiment from Sir Ifaae * 
Newton 9 which I repeated on Account of what is 
laid in Rizzett? s Preface, Rage 1 <5, viz. that if 
{according to Sir Ifaae) Rays were differently reflex - 
Me, Colours muft be produced by Reflexion from a 
plane Surface ; but this , fays our Author, is contrary 
to Experience . Now this his Aflertion is difproved by 
. Experiment IX. 
As this Experiment was made exadly in Sir Ifaae 
Newton's Manner, and with the fame Succefs, I re- 
peat the Account of it in his own Words. 
“ Let H F G [ in Figure 20] reprefent a Prifm in 
the open Air, and S the Eye of the Spectator, view- 
“ lfig the Clouds by their Light coming into the Prifm 
c at the plane Side F1GK, and receded in it by its 
“ Bafe H El G, and thence going out through its plane 
- Side HEFK to the Eye : And when the Prifm and 
« Eye are convenient ly placed, fo that the Angles of 
« Incidence and Refledion at the Bafe may be of about 
* 40 Degrees, the Spedator will fee a Bow M N, of a 
<c blue Colour, running from one End of the Bafe to 
w the other, with the concave Side towards him, and 
O 000 the 
