X Am ) 
i fV that all the Sedions parallel to the Axis make the fame Pa* 
I rabola* 
I Thus far M. Hugemus his judicious Letter 5 to the latter part 
of which, concerning the grinding FarabQlical Conoids^ Mr. 
\NemoniMh^ in his Letter to the Publiflier of Feb. 20. 71. 
I that though lie with him defpairs of performing that work by 
1 Geometrical rules, yet he doubts not but that the thing may 
I in fome meafure be accompliflied by Mechanical de- 
I vifes. 
I To all whuh I cannot but fubjoynan Extra& of a LeUer^ receimd 
,i very lately^ {March 1 9th) from the Inventor ef this new Te- 
, hfc9pe^ /r(?/w Cambridge, vin^. 
IN my laft Letter I gave you occalion to fufped, that the 
Inftrument which I (ent you, is in fome refpeft or other 
, indifpofed, or that the metals are tarniflied. And by your 
Letter of March 16^ I am fully confirmed in that opinion.For, 
whileft I had it^ it reprefented the Moon in fome parts of it as 
diftindily, as other Telefcopes ufually do which magnifie as 
much as that. Yet I very well know, that that Inftrument 
hath its imperfeftions both in the compofition of cbemctall^ 
I and in its being badly caft, as you may perceive by a fcabrous 
place near the middle of the metall of it on the poliflied fide, 
and alfo in the figure of that metall near that fcabrous place. 
And in all thofe refpefts that inftrument is capable of further 
improvement^ 
Youfeem to intimate, that the proportion of 38 to i holds 
only for its magnifying Objefts at fmall diftances* But if for 
luch diftances, fuppofe 500 feet, it magnifie at that rate, by 
the rules of Opticks it muft for the greateft diftance imagi- 
nable magnifie more than 57I to 1 5 which is fo confiderable 
a diminifliing , that it may be even then as 38 to i , 
Here is made another Inftrument like the former ^ 
which does very well Yefterday I compared it with a fix 
f oot Telefcope, and found it not only to magnifie more, but 
alfo more diftinftly. And to day I found, that I could read 
in one of the Philofophical TranfaSiom^ placed in the Sun*s 
LUI 1 lighf^ 
