Ci24) 
I wifti) Ihadafccret in opHcks to encourage him to that 
cottiaiunication. If I did bclicvc> that this would be cftee- 
medone. To meafure with a great Telefc^pe th^dijianc e of 
Obje&s upon the Earth s which I have found long fincCj and 
propofed to fome by way of Paradox 3 Lgcorum diftantias 
exunica ^atione^ ahfque nllo Injirnmento Mathematico^metirth 
I doc here promife to difcover it to him, with the neceffary 
Tables, as foon as He (hall have imparted his to mc^ which 
I willufe, as he {hall order me. For, although the Fra3ije 
doe not altogether anfwcr the TA^<?rjrof my Invention, be- 
caufcthat the length of the Tele/copes udmits of fome Lati- 
tude ^ yet one comes near enough, and perhaps as Juft, as 
by moft of the wayes , ordinarily ufed with Inftrumenis. 
That, which I am propofing, I doubt not but M. Hoo!^ will 
foon undcrftaod, and fee the determination of all Cafes 
pofsible. I fhall only fay, that if we look upon the folc The- 
ory^ we may make ufe of an ordinary Telefcope^ whereof the 
Bye^glafs is to be Cof^vexetfoTy by putting the Glafles at a lit- 
tle greater diftance,^ than they arej proportionably to the 
diftance for which it is to ferve , and by adding to it a f^ew 
Eje-glafs^ the Objefl: will be feen diftinft, though obfcure 5 
a.nd if the EyC'-glajs be Cohvexe^ the Objeft will appear ereft. 
They may be done two manner of ways 5 either by leaving 
the Teiefcope in its ordinary fituation , the OhjeS-glafs before 
the Ej/g'glafj^ or by inverting it, and putting before 
tHat. But if any will make ufe of two O^yVfl^-j/^/e/, where- 
of the Focus's are known, the diftance of them will be 
known. Ifitbefuppofed, that theF^wof the Jirfih^ B. 
and that of the fecond C. and the diftance given, B t 2 
and that D minus C. be equal to F 3 for^* this diftance^will be 
e^//^/toB + C + F-TF*C*, And if you have the F^r^/ of the 
frfiOhjeB-glafs^ equal to B, the diftance, where j^ou will 
put iihc feco^d Glafs equal to B 1 6 + D. the focus of the 2d 
Glaffc will be found equal to And if you will that the 
Objeft (hall be magnified as much with thefe two Glafles, 
as it would be with a fiogle one , whereof the Focus 
fiiould 
