230 Mr. Brougham’s Experiments and Observations on 
by the deflecting force, each having one focus in the centre of 
the body. The truth of these things mathematicians will 
easily determine. 
Prop. VI. If a ray fall on a specular surface, it will be bent 
before incidence into a curve, having two points of contrary 
flexure, and then will be bent back the contrary way into an 
equal and similar curve ; as in fig. 1. (Tab. VII.) 
Corollary to these propositions. If a pencil of rays fall con - 
verging on an interposed body, the shadow will be less than 
the body by twice the sine of inflection. 
And if a pencil fall diverging on the body, the shadow will be 
greater than the body by twice the sine of inflection ; but less 
than it should be, if the rays had passed without bending, by 
twice the sine of the difference between the angles of inflection 
and incidence. — The sine or angle of incidence is greater than 
the sine or angle of inflection, when the incident rays make 
an acute angle with the body ; but when they make an obtuse 
or right angle, then the sine or angle of inflection is less than 
that of incidence. The sine of incidence is greater than that 
of deflection, if the angle made by the incident ray with the 
body is obtuse, but less, if that angle be tSute or right. — If a 
globe or circle be held in a beam of light the rays may be 
made to converge to a focus. 
Hitherto it has been supposed, that the parts of which light 
consists have all the same disposition to be acted upon by bo- 
dies which inflect and deflect them ; but we shall now see that 
this is by no means the case. 
Obs. 1. Into my darkened chamber I let a beam of the sun’s 
light, through a hole in a metal plate (fixed in the window-shut) 
of ^th of an inch diameter ; and all other light being absorbed 
