The Prerace. 
fick gravity # ofto efficacy.By this [have alfo found, that look wbat pro- 
portion the Sine of the Angle of one Inclination has to the Sine of the 
Angleof Befrattion, correfpondent toit, the fame proportion have all 
the Sines of other Inclinations to the Sines of their appropriate Refr actions, 
My way for meafuring how mucha Glafs magnifiesan Objet, plac’d ata 
convenient diftance from my eye,is this. Having rectifid the AG@cro/cope, to 
fee the defir’d Object through it very diftin@ly, at the fame time that I look 
upon the Obje¢t through the Glafs with one eye, [look upon other Objects » 
at the fame diftance with my other bare eyes by which meansI am able, 
by the help of a Ruler divided into inches and {mall parts, and laid on the 
Pedeftal of the Microfeope,to caft,as it were, the magnifi'd appearance of the 
Object upon the Ruler,and thereby exactly to meafure the Diameter it ap- 
pears of through the Glafs, which being compar'd with the Diameter it ap- 
pears of to the naked eye, will eafily afford the quantity of its magnify- 
ing. Oi db 
: “The Microfcope, which for the moft part I made ule of, was fhap'd much 
like that in the {ixth Figure of the firft Scheme, the Tube being for the moft 
part not above fix or feven inches long,though, by reafon it had four Draw- 
ers, it could very much be lengthened, as occafion required 5 this was con- 
triv'd with three Glaflessa {mall Object Glaf$ at A,a thinner Eye Glafs about. 
B, and a very deep one about C: this [made ufe of only when I had oc- 
cafion to fee much of an Object at once; the middle Glafs conveying a 
very great company of radiating Pencils, which would go another way, and 
throwing them upon the deep Eye Glafs. But when ever I had occalion to 
examine the finallt arts of aBody more accurately, I took out the middle 
Glafs,and only made ufe of one Eye Glafs with the Obje& Glas, for always 
the fewer the Refractions are, the more bright and clear the Object appears. 
And therefore ‘tis not to be doubted , but couldwe makea Affcrofcope to 
have one only refraction, it would, ceteris paribus, far excel any other that 
, had agreater number. And hence it is, that if you take a very clear piece 
_ of a broken Venice Glafs, and ina Lamp draw it out into very {mall hairsor — 
' threads, then holding the ends of thele threads inthe flame, till they melt 
and run into afmall round Globni, or, drop, which will;hangat,the efid of 
the thread 5, and if further you ftick feveral of thefeuponthe end of aiftick 
with a little fealing Wax, fo as that the threads ftand upwards, andthenon 
a Wherftone firft grind off'a good part of them, andsafterward ona {miooth 
Metal plate, with a little Tripoly, rub them \till:they come to be. very 
{mooth; if one of thefe be fixt witha little foft Wax again{t afmall needle 
hole.priek’d through a thin Plate of Brafs, Lead, Pewter, or any other Me- 
tal, and an Object, placid very near, be Jook'd \at through it, itwillboth 
magnifie and make fome Objects more diftinét then any of the great Aficro- 
Scopes, “But becaufe thefé, though exceeding cafily made, are yet verytrou- 
blefometo be us'd,becaufe of their fmalnefg,and the nearnefs of the Object; 
therefore to prevent both thefe, and yet ha ve only twoRefractions; Lpro- 
vided me a Tube of Brafs, fhap'd much like that in the fourth Figure of the 
firft Scheme ; into the fmaller end of thisI fixt with Waxa good plane tom? 
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valk 
