1^4 MifceUanea Curio fa. 



Which things {hew, that the Art of duly applying 

 tight to the ObjeB does very much help and improve 

 Vifion. So alio does the due placing of the Obje&> 

 as to Height and Diftance. But to enumerate 

 all things that help DireSl Vifion, would be infi- 

 nite. 



2. Ex parte Organi vel Medii, Direct Vifion has 

 been improved by making u(e of a Tube, without 

 Glaffes, or a Man's clos'd Hand, to look thro' ; 

 which admitting into the Eye only the principal 

 Rays, that come dire&ly from the Objt£t, do 

 very much ftrengthen and clear the Sight, by 

 excluding all the Collateral Rays, that crouding 

 into the Eye, together with the direct ones, 

 Would confound and difturb it, partly by mixing 

 and interfering with the direct Rays, and partly 

 (or rather chiefly) by too much enlightnirg the , 

 fund of the Eye, wherein Vifion is truly (tho* 

 then imperfectly ) made. 



On this is founded the Art of making Spetta- 

 des without GlaiTes ; (as well as Tubes) which is 

 done by putting into the Glafs-holes (inftead 

 oF Glaffes) two fhort Tubes of between three 

 and four Inches long (for their length is to be 

 vary'd according to the Age or Eye of the Be- 

 holder, and (b alfb is the Diameter of the ex- 

 tream ends) which Tubes being made of Spanifh 

 Leather (or Paft-board, or fbme fuch like Mat- 

 ter) and black'd on the infide, are fo to be pla- 

 ced, as that the vifual Rays, receiv'd thro* them, 

 may meet in one point (or rather iflue out from 

 one Point) of the Object, ftanding at fuch a due 

 diftance, as the Perfbn may clearly and diftinctly 

 fee it, or according to his length of Sight (as 

 ABC, in the 4th Fig* Tab. g.) 



And 



