■ ( 4^59 ) 
inftrument will be but fmall^the object dark aod confufedjand 
alfodifEcuk tobefound. NordoUeej why the reflexion is 
more upon the fame axis^^ud io more natural in one cafe than 
in the other : fiace the axis it felf is reflected towards the Eye 
by the Oval plain 3 and the Eye may be defended from ex- 
ternal light as well at the fide, as at the bottome of the Tiibe4, 
You fee therefore^ that the advantages of this defign are 
none, bat the diladvantages fo great and unavoidable, thrt^ 
fear it will never be put in pradtile with good efFed:^ And when 
I confider, that by reafon of its refemblance with other Te« 
Idfcopes it is (omc thing more obvious than f he other couftrud:* 
ion • I am apt to believe, that thofe^who have attempted any 
thing in CatopCrickSj have ever trycd it io the firfl: placeg aod 
that their bad luccefs in that attempt hath been the caufe, why 
nothing hath been done in reflexionr, ForjMr. Gregory^ ipQ^ik- 
ing of thefe inftrtiments in the aforefaid book pag 9 fayethi 
De mechanica horum fpecnkrum & leniium ^ ab aliis frujirs tentd^ 
ta^ ego in mcchmuts minus verfatus nihil dico» So that there have 
been tryals made of thefe Tclefeopes, but yet in vain* And I 
am iofori33ed5that about 7 or 8 years fioce^Mr. Gregory himfelf, 
SLi Lonclm^cmkd one of fix foot to be made by Mr» Heive^ 
which ! take to have been according to the aforefaid defign 
defcribed in his book 5 becaufe^ though made by a skilful Ar» 
tiftj yet it was without fuccefs. 
I could wifli therefore ^ Mr^ Capgrmn had tryed h s defign 
before he divulged it/ But if/or further fatisfa&ion^ he pleafe 
hereafter to try it , 1 beUeve the fuccefs will inform him, that 
fuch projedsare of little moment till they be put inpradife^ 
Some Experiments pr@p0s'd in reiation to Mr,, Newtons Theorjiof 
. light rimed 2>2 Numb, 80 ^ together with the Obfervatims made 
thereupon by the Author of that Theory j cemmum^ated in a 
Letter of hii from Cambridge, April 1^. i6j2^ 
I. >^"T~^ coatra(9: the beams of the Son without the h©leof 
the u^indow^ and to place the prifm between the 
focus of the Lem and the hole/pokeu of in M^NeTPt^ns theory 
of lighr^ 
II,, Yo 
