( 4^57 ) 
you 1 have lefs difficulty mdifcovering the Qbjeds than ia 
that of Mr, JNeiPiom. 
A 
So far this French Author, To which we jhall mtv Jiibjoin the 
Confiaeratims of Mr. Newton ^ tutve received them from hm 
inaXetter, written from Cambridge Amy ^.th iS/i^m fdloms, 
SIR 
T Should be very glad to meet with any imprcveunsot of 
|_ the Catadioptrical Telefcope; but that dtfignof ir^which 
( as you informemejlVlr.C^^^ra/;^hath Gommunicated 3 months 
fince, and is now printed in one of tbeVreuch Memoires,^ 1 
fear will not anfwcr Expeftation. For, when I firft applied my- 
(elf tp try the effefts of Reflexions^ Mr. Gregurys Optica Pro* 
f^ota {^x'miQA intheyear 1669 ) being fallen into my hands, 
where there is an Inftrument ( defcribed pag* 94 ) like that 
of Monfieur Ca^egrmti s with a hole in the midftot the Objeft- 
Metal to tranfmit the Light to an Eye-glafs placed behind it § 
I had thence an occafion of confidering that fort of conflrudii- 
ons, and found their difadviantages fo great, that I faw it ne- 
cefTary, before I attempted any thing in the Pracftiquej to al- 
ter the defign of them, and place the Eye glafs at the fideol 
the Tube rather than at the midle* 
The difad vantages of ityou willunderftand by thcfe parti- 
culars. i^There will be more h'ght loft in the Metal by reflexion 
from the little comttf^eculum^ than from the Oval plane. For^ 
it is an obvious obfervation, that Light is moft copioufly rc» 
flefted from any fubftance when incident moft obliquely.lThe 
convex Speculum will not refledt the rays fo truly as the oval 
plane, unlefs it be of an Hyperbolique figure ^ which is in- 
comparably more difficult to fojSne than a plane s and if cro« 
R r r r 2 ly 
