£52 Mr. Brougham’s Experiments and Observations on 
particles so blended as to be increased in size ; for the number 
of separate rays thrown into one place will not increase their 
intensity sensibly. The other objection is, that passage in 
Newton, where he says “ that the orange and yellow are the 
“ most luminous of all the colours, affecting the senses most 
“ strongly/’* Now, besides that this is an assertion opposed 
by the positive experiment just now quoted, I think an answer 
may be thus made to it ; the whole light, from which the 
spectrum is never free, which inclines to yellow, and which is 
composed also of red, abounds in the yellow and orange of the 
spectrum ; so that both of these colours derive their superior 
lustre rather than intensity from this circumstance ; or if 
they have any degree of the latter more than the red, it is in 
fact owing to their mixture with the red and the other rays, 
which are all in the white. 
Having endeavoured to unfold the property of flexibility, as 
varied in inflection, deflection, and reflection; and also the 
physical cause of this property; and having indulged in a 
speculation depending on this cause, I flatter myself neither 
altogether useless nor unimportant, I hasten now to the na- 
tural phsenomena, the explanation of which depends on the 
property, whose existence and nature we have just now been 
investigating ; and that we may treat this part of the subject 
with conciseness and order, we shall rank the phaenomena un- 
der a division similar to that under which we laid down the 
principles, beginning with those appearances which are expli- 
cable on the principles of flexion. 
i. It is observable, that when a body is exposed in the 
sun’s light, so as to cast a shadow, and another body is ap- 
* Optics, Book I. Part I. Prop. 7. 
