( 4 37 ) 
than that of the red Half, and the Blue or Purple of the 
red Haif &en thro 5 the Prifm was lefs intenfe than that of 
the biue Half. 
N. ts. If the Ribbon or Worded is laid upon any en- 
lightned Body, the Phenomenon will not fucceed (o well; 
the Colours of the Body feen thro’ the Prifm mixing with 
thole of the Ribbon or Worded. Even a black Body will 
not do, if Light falls upon it : but there mud be a black 
Cloath behind, in fuch manner that no Light falling up- 
on it can be refledled (o as to didurb the Phenomenon. 
And if a (hort-fighted Perlon looks through the Prifm, a 
concave Lens between his Eye and the Prifm will render 
the Phenomenon more didindt than it wou’d otherwilebe. 
EXPERIMENT II. 
Some Days after, the Sun Aiming, I made two Holes 
n, K in the Window Shut S s, of a darkned Room 5 
thro’ which letting the Suns Beams pafs, by means of two 
Prifms A, B, (one near each Hole.) I open’d the Rays co- 
ming from the. Sun into the two colour’d Speftra a, / 3 , 
where the following Colours were very didintd, vi%. Red, 
Orange, Yellow, Green, Blue, Purple and Violet. Now 
the Reafon of their being more didindi than ordinary, 
was, that the Prifms which I made ufe of were made of 
the greenilh Glafs mentioned before ; which is very free 
from thole Veins by which the Colours are too much 
thrown into one another, by the bed white Prifms of the 
common fort. 
The foremention’d colour’d Spefir* being thrown into 
the Room, to the Didance of about zo Feet from the 
Window where the Sun’s Light came in, 1 caus’d a Piece 
of white Paper 7 r, ~ Inch broad and 5 Inches lony, to be 
held within the refradied Ray , (at the Didance of 10 
Feet from the Windows,) which produc’d thefe Colours 
in fuch manner, that by turning the Prifms round their, 
Axes 
