r 4005 ) 
e D an Ifoii wire ^ holding a ring of brafsj m whicli the 
Ifpeculum CD is fixcd^ 
' Fja fraall Eye-glafs flat above^ and convex below^ of the 
twelfth pare of an inch radws^ if not lelsi forafmuch as the 
metal colleiis the Sun's rays at 6f inches diftance, and the 
' Eye-glals at lefs than i of an inch diftance from its vertex : 
'Segdes that the Author (as he informis us) knew their di- 
Imenfionsby the tools to which they were grouudj and par* 
ticulaily meafuring the diameter of the hemi-fpherical Gon- 
' cave 5 in which the Eye-glafs was wrought^ found it the fixtb 
^ part of ao inch. 
' G G G, the fore part of the Tube faftn d to a brafs^ring; 
H to keep it immoveabie* 
' P^^^>, the hiod'parc of the Tube^ fafta'd to another 
'brals-ring P 
I o,an lron hook faftn'd to the Ring and furniflit 
with a fcrew N, thereby to advance or draw back the hind» 
ipart of the Tube, and fo by that means to put the^^^^^ 
in therr due diftance. 
I M^t?/ a crooked Iron fuftaining the Tube^ and fafe 
ined by the nail R to the Ball and Socket S » whereby the 
1 Tube may be turned every way. 
; The Center of the flat fpetulnm CD ^ miift be placed in ; 
the fame point of the Tube's Axe, where falls the perpsn- 
fdicular to this Axe, 5rawn to the fame from the center 
'of the little Eye*glals : which point is here marked^ 
! at T.- 
And to give the Reader fome fatisfaftioti to onderftand, in 
what degree it reprefents things diftindlj and free from eo* 
lours, and to knew the aperture by which it admits Hght ^- i 
ibe may compare the diftances of the fecus E from the ^^<?r- 
nx's of the little Eye-glafs and the Coticzvcfptculumy that is, 
EF, i:of an inch, and ET V^ 6t inches; and the ratioy\\k\ 
be found as I to g8 5 whereby it appears , that the Obje^i 
will be magnified about 58 times. To which proportion h 
very confentaneous, an Obfervation of the Crown on the 
weather-cock,about 500 feet diftaRt.Fpr the fcheme X fig.^. , 
reprefencs it bigger by 2i times in diameter 5 when feen 
