398 
Transactions of the Society. 
that the larger the amount of the material that is illuminated, the 
greater will be the brilliancy of any individual point. 
The photometry of bull’s-eyes and illuminators may appear in 
itself to be a matter of small consequence, but the investigation of 
the dark-ground illuminator points to results as regards reflection 
and its surprising influence on illumination, that suggest considera- 
tions concerning the cause of glare and mistiness in ordinary 
observation which may lead to important modification in our ideas. 
