(219) 
to my darkncd Chamber, to fee thofe various PhaBnomena of Light 
madeby divers Refraflions and Reflexions, and took Notes upon 
thera; which induftry if they al fo had ufed^who endeavour to expli- 
cate the aforefaid difference between the length and breadth of this 
coloured SptSirnm^ by the received Laws of RefraSion, would ne- 
ver have taken fo impoffible a task in hand. 
The reft is^Honoured Sir,that it is far ftom vsy intent,that the mi* 
ftake here mentioned do any way derogate from that learned perfons 
Which truly might have happened to my felf, if at my firft tryai 
thereof,the Sun had been in a white cloud^as it feems,it happened cq 
him* Wherefore ceafing further to trouble you, I reft, 
Yours to command, . Franii^lJinus. 
r'- 6 0aob.f674. 
Sir, Anf^er to this Letter. 
TH E Letter you thought fit to write by way of Animadverfi« 
on upon Mr. iV>)37/a/^'s new Theoty of Light and Colors, 
grounded upon an Experiment of letting the Sun-beams through a 
little bote into a dark chamber, feems to need no other Anf v^^er but 
this, That you would be pleafed to look upon and confider the 
Scheme in Ur.Newto?is 2d Anfwerto P.Fardies 'm NumkSS'^f^^^ 
Fhf[ran[diiion$\diVid reft affuredjthat the Experiifient,as it is repre- 
fented, was tryed in clear days, and the Prifm placed clofe to the 
holein the window,fo that the Light had no room to diverge,and the 
colour'd Image made not parallel (as in that conjefturc) but tranf- 
vcrfe to the axis of iht Prifm# 
hcndoH^ Decemb. 17.1674. 
B:ctra!fsoftmLetters^ mitten by Mr, Flamfte^d Mr. Collins 5 
the one ^/Novemb. 25.1624. concerning m Injlrument fo Jhew the 
Moons true place to a mimte or two ; as alfo the Writers s defgn of 
correcting the hitherto affignd Motions of the SuniThe other,i?/Dc^. 
cemb. 14. 1674. touching the mcejjitj of making Nevo Solar JSfum* 
bers^ together with an Expedient for making trial^whether the Re^ 
fractions in Signor CafllniV Tables are ju^. 
The ExmU of the &r{i Letter. 
AFter my return toVerbj^ fell to perufe Mt.StreefsT)\^coMxfc^ 
and to confider the Contrivance ^hsMoon-wifir^ which 
though he affirms in the Conclufion of his little Traa-,to be different 
from 1Au¥Iorroxes\^tt \ can affure^that for the Motion of Lpngitude^ 
'tis the very fame, and no other than what is taken from my Expli- 
catio|[V^fave that,where I thought the manner of Librating the Jpoge* 
um was obvious from the Calculation, and needed not to be ex- 
K f 9. Dlained- 
