28

(see drawing in Ms)

[Grazing]

α = 90° nearly — v. bright & colourless

α = 75° - rich red - purple - on closer Exam nos. of little red & blue spots

α = 60°   rich blue purple — sm. red spots on blue grounds

α = 45°   rich blue purple with almost no red spots.

α = 30°  rich blue with greenish glisten

α = 0°    blue green with very bright yellowish green spots.

28v

(see drawing in Ms)

α = 75°   Bright green

α = 45°   yellow green  lines betw. fibres v. black  

as α diminished the feather almost ceases to reflect light

(see drawing in Ms)

α = 60° or 70°

Green  with greenish lustre

α = 45°

 green with slight bluish lustre

29

bluish green in all lights brighter when α is small

(see drawing in Ms)

α = 0°      Black blue

        2        1

α = 45°   Dark purple blue

α = 30°   Purple red   rich

   2        1

α = 90°   red purple redder

30

α = 90°   near blue far side green blue α = 45°  blue green α = 0°   bright green1