372 M. C. Lea on certain phenomena of Light. 
of phase, and not that reflected at the second, Thus in either 
case, whether the particle have a greater or less index than the 
medium, there will be a difference of phase equal to half an os- 
cillation between the rays reflected at the two surfaces, inde- 
pendently of the thickness of the particle, and this wi 
minute particles will always lead to the remit of blue 
light by the interference of the two reflected 
ere is one condition that will be sacaiiadiall plavonbhe for 
the production of red light by rays both of which pass through 
the particle and of blue light by rays reflected at the front and 
back surface: this is when the particles have a — form, 
appear from the following consideratio 
Let direct rays of light, L, L’ strike any cohites 8. a 
a —— nearly in the di- 
n of a diameter will be 
eecicpally transmitted. Oth- 
ers striking more vega at 
any point ~O will be la argely 
reflected. As there are many 
globules, there will result a 
bundle of rays R RR’R, and 
similar pa abe 
’ 
' 
' 
1 
! 
' 
‘ 
be irregu- - 
larly ert - all angles ae 
and directions ; for rays L’O p 
will strike at t all aie of the ~ 
front hemisphere of the globule S. ist us consider any one 
set of parallel rays RR BB. These will strike other spheres 
and each sphere will receive rays like R’ following the course 
of a diameter. At M a portion of the light will be reflected 
a portion will pass into sos sphere, see of which 
swe a much larger 
proportion of the incident rays are caused to interfere in - 
= of cranes es than of those that are angU 
be sufficiently small, this will result in the 
production of bu ight returned in some direction M RB’. If 
the spheres be of irregular sizes, the blue li light ht will be m more OF 
= i diluted with white, ‘These results will follow whether the 
ea eee ers ie ss 
ee a | OM ee eter ee Penn ae 
Bree ayn ee ae ea ane MER Be 
