( 44 * > 
the Wires, and fix’d it to a fmail Board juft broad enough to 
(land fall. See/v*-. 14. 
EXPERIMENT V. 
I took the Prifm C D, and thro’ it look’d at the colou- 
red Spectrum R P, which appear’d then round and white as 
at S, juft asifit had been the Sun’s Light received on a 
Paper from the Hole H, and feen with the naked Eye. In 
this cafe the Prifm C 0 muft be held in direftum with A B, 
and the refra&ing Angies in the two Prifms muft be equal. 
This Speftrum appearing white but juft in one Point, is 
not fo readily found ; but the beft way is to look thro’ 
the fame Prifm A B which makes the Speftrum, which may 
eafily be done if it be pretty long, and then R P will be 
feen white and round, and as at S f as if coming dfredtly 
from//. SeeFig. ty. 
EXPERIMENT VI. 
I held a broad Lens L l, ground to a Radius of i ~ Feet, 
in fuch manner that the whole colour’d Speftrum fell upon 
it ; and after Refracftion all the Colours appear’d to con- 
verge, if receiv’d on a Paper at p p ; but when the Paper 
was held in the Focus at /mu the pofition tt Ftt, the bpe- 
ftrum was round and perfectly white by the Union of all 
the colour’d Rays. If the Paper vyasheld at n i^, the Co- 
lours appear’d to diverge from each other, but then the 
Red was uppermoft, which before us’d, to be the lo weft, 
and fo on in an inverted", Order.. : 13( 3 , 
I try’d the fame Experiment wljtjh a Lens of one Foot 
Radius, with one o£ ,9 Inches, and with another of 7,. 
and the guccefs was; the fame. v . See-the i 6 th Figure, 
whexethe R , 0 , T, G, B }r P, V, exprefs the Colours. 
N. B, 
