< 45 8 ) 
Axes, 1 cou’d make the red Ray of the Spetfrum, made by 
the one Prifm fall upon one half of the Paper, and the pur- 
ple Ray of the SpeBrum made by the other Prifm 
fall upon the other Half ; for the SpcBra were both 
vertical, the Lines which terminated the long Sides of 
them towards each other juft touching, as appears in Fig. 3 . 
Then at the Diftance of 9 Foot, looking thro’ the Prifm 
C at the Paper thus colour’d, the red Half appear’d very 
much feparated from the Purple, the one feeming lifted 
up from the other ; the Red or the Purple appearing the 
higheft, according as the refra&ing Angle of the Prifm 
was either held upwards or downwards. The Phenome- 
non is much more diftineft this way than any other ; for 
-the Paper not only feems divided into two, when it is co- 
loured by a red and a purple Ray, but alfo by a Red and 
Blue, ( Fig .4.) by a red and a green Ray ,(Fig. 5 >) or indeed 
by any twoColours that are different, how near foever their 
Places in the SpeBra be to each other. The Halves of 
the Paper appear, when view’d thro’ the Prifm, to be farther 
from each other, when the Paper is ting’d withfuch Colours 
as are farther from each other in the Series of Colours in 
the SpeBrum : and neareft, tho’ftill divided, when neigh» 
bouring Colours fall upon the Paper, as Yellow and Green, 
or a light and a deep Green. But the Paper appears no 
way divided, when colour’d with the Red of the two 
SpeBra, (Fig. 6 ,) if thofe Reds are equally intenfe : and fo 
of the other Colours. 
EXPERIMENT III. 
I held a Lens of about 3 Foot Radius at the Diftance 
of Six Feet from the oblong Paper (on which a red and 
purple Ray falling, made it look half Red and half Purple) 
2nd 1 projected the Imagp of the faid colour’d Paper at the 
Diftance of about Six Foot on the other Side of the Lens> 
on 
