A Treatise on the Kaleidoscope

angle A O B angles of incidence angular aperture angular point aperture apparent magnitude applied beauty brass rim catoptric centre CHAP circle circular field coloured glass combination composed constructed convex lens direct vision distance effects produced equal exhibited eye end field of view figure fixed flectors focal length fragments gular half Hence images formed inches inclination Indigo instru instrument intensity inverted image ject Kaleido Kaleidoscope last reflected last sector leidoscope lens light looking-glass m n o p magnitude manner ment mirror A O motion move number of reflections number of sectors object plate odd aliquot optical ornaments pattern pieces plane mirrors polygon position principles rays rectilineal reflected images regular polygon ring rors round scholium screws seen by direct semitones shewn in Fig shews side specula speculum speculum metal square stationary surface symmetrical picture symmetrically related three reflectors tion transparent triangle tube velocity window shutter