28

(see drawing in Ms)

[Grazing]

α = 90º nearly — v. bright & colourless

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

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

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

α = 30º  rich blue with greenish glisten

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

28v

(see drawing in Ms)

α = 75º   Bright green

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

as α diminished the feather almost ceases to reflect light

(see drawing in Ms)

α = 60º or 70º

Green  with greenish lustre

α = 45º

 green with slight bluish lustre

29

bluish green in all lights brighter when α is small

(see drawing in Ms)

α = 0º      Black blue

        2        1

α = 45º   Dark purple blue

α = 30º   Purple red   rich

   2        1

α = 90º   red purple redder

30

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