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the ether, the actual times of vibration depending however 
upon the molecular forces in the body. As these atomic 
vibrations will again affect the ether, such bodies will or may 
become luminous, the wave lengths of the emitted light being 
however longer than those of the incident light which causes 
the disturbance in the body. 
This emitted light will necessarily last some time after the 
incident light is removed, for the vibrations in the body will 
not cease as soon as the cause of disturbance is removed, but 
in general it is to be expected that this emitted light will 
speedily disappear, though cases may occur in which it will 
continue for a considerable time. 
These probable deductions from the assumed principles 
coincide exactly with the phenomena of Fluorescence and 
Phosphorescence (not including in this term cases in which 
light is emitted by bodies undergoing slow combustion), all 
Fluorescent bodies being Phosphorescent for times of different, 
though in all cases at present observed, of very short duration. 
PHYSICAL AND MATHEMATICAL SECTION. 
November 9th, 1865. 
E. W. Binney, F.B.S., F.G.S., President of the Section, 
in the Chair. 
Mr. Baxendell, F.R.A.S., read the following " Note on 
the Variable Star S Delphini.” 
Since the discovery of this variable in October, 1863, it 
has gone through two complete periods of change, and my 
observations have enabled me to fix with tolerable exactness 
the dates of three maxima, and to determine the form of the 
light-curve for that portion of the period during which the 
