The Monthly Microscopical"! 
Journal, January 1, 1869. J 
NOTES AND MEMOEANDA. 
57 
Sir David Brewster, in a paper on the ' Principles of Illumination of 
Microscopic Objects,' published as far back as 1831, says : — 
" TJie eye should he ])roteded from all extraneous light, and should not 
receive any of the light which proceeds from the illuminating centre, ex- 
cepting that portion of which is transmitted through or reflected from the 
object. The light which is employed for the purpose of illuminating the 
object should have as small a diameter as possible.'^ And again in the 
same paper: — " J?2 the illumination of microscopic objects, ivhatever light 
is collected and brought to the eye beyond that which is fully commanded 
by the object-glasses, tend rather to impede than to assist distinct vision." 
These are the principles laid down by Sir David Brewster, and 
they are by no means obsolete, although his ideas of carrying them 
out certainly seem rather crude at this time of day, when science has 
made such rapid strides. For instance, he says : — " For illumination at 
night a common bulVs-eye lantern may be used with great advantage." 
It has seemed very strange to me that Sir David's principles 
should have been acknowledged so long without any adequate attempt 
being made to arrive at perfection in carrying them out practically, 
and I turned my attention to the subject. I am not vain enough to 
imagine that the lamp I have invented will never be improved upon 
or superseded by something more perfect ; but from opinions I have 
had from those whose experience renders them competent judges, I 
think I may fairly claim for my lamp the merit of being the most 
effective microscope lamp yet invented. As will be seen from the 
