( 5084 ) 
Ifiaac Newtons An[wer to fame Conjiderations upon his Do-. 
Brine o/Light and Colors 3 vdhich DoUrine was printed in 
Numb. 80. of the/e traUs, 
S1J{, 1 have already told you, that at the perufal of the con- 
fiderationsj you lent me, on my Letter concerning Refrac- 
tions znd Colors^ I found nothing, that, as I conceived^mighc 
not without difficulty be anfwer'd. And though I find the 
Confiderer fomewhat more concernM for an Hypoth^fisy than I 
expeded yet I doubt not, but we have'one common defign , 
I mean, a finccre endeavour af cer knowledge, without valumg 
uncertain fpeculations for their fubtleties, or defpifing cer- 
tainties for their plainnefs : And on Confidence of this it is, 
that I make this return to his difcourfe.* 
The/r/? thing that dfF::rs it felf 
'^Whkhv:\{cmxii^At thought fpf. ;,r,ree^hle tome auA \ Kpn-ii-i 
f,,uu\s tobe hereprmud at len jh, !=> itis agreeaDie CO me, and I begin 
hecaufein the body of this y.nfvJer With It beCaUie It IS \o. The Confi- 
are to h met with the chief particu' j^^^j. jg pjeiafed to reprehend me 
for laying ahde the thoughts of im- 
conctrn 
proving Optiques by R^fraBions. 
^^ofiUif.aa,^, pm rf ot. he had Obliged me by a private 
Letter on this occafion^ 1 would 
Iiave acquainted him with my fucceffes on the Tryals I have 
made of that kind, which I fliatl now fay have been lefs than 
I fometimesexpeiStedjand perhaps than he at prefent hopes 
fbr. But fince he is pleafed to take it for granted, that I have 
let this fubjeilpafs without dueexamination, I fliall refer him 
J . V. 1. o r ir to my former Letter, by which 
* Printed tn Numb. 8o. sf thefe ^ *^ • xi -if i 
j-^^^s, that conjecture will appear to be 
uD-grounded* For^^ what I faid 
there, was in refpefl: of Telefcopes of the ordinary cpnftrudi* 
on, fignifyingj that their improvement is not to be expected 
from the welUfiguringoi Glaffes, as Opticians haveimagin'd 
but I defpaired not of their improvement by other conftru- 
dlions 3 which made me cautious to infert nothing that might 
intimate the contrary* For, although fucceffive refractions 
that are all made the fame v^ay, do necefTarily more and more 
augment the errors of the firft refradion 5 yet it feem'd not 
impofTibleforro/z^r^y refradlions fo to corre(3: each others 
inequalities, as to make their difference regular 5 and, if that 
^ could 
