MICROSCOPIC OBJECTS. 207 



the kind of light wanted, and from its length will be sure 

 to fill the largest field with the lowest power with it. I 

 do not think condensers or concave mirrors necessary 

 with the Megaloscope, because its own natural light is so 

 great. 



There are few, I think, who must not have observed 

 the beautiful effect produced by the mild radiance of the 

 declining sun streaming through the glades of a forest, 

 and fighting up the blades of the grass and the leaves, 

 and on the majestic trees, with that indescribably briUiant 

 and tender green which can be compared to no other 

 eartlily green. Now if we examine into the nature of 

 this illumination, we shall find that it is always lateral and 

 oblique — in short, just of the same nature as that called 

 the black ground illumination ; only the rich yellow fight 

 of the sun, when it is sufficiently low down in the horizon 

 to permit our eyes to gaze on its disc with impmiity, far 

 surpasses in beauty anything else we are acquainted with ; 

 whatever transparent objects it may iUumine it touches 

 with a heavenly tint, which has been the theme of poets 

 in every age and country. 



I have repeatedly observed, and all microscopists know, 

 that the fufi fight of the sun cannot be modified so as to 

 suit microscopic purposes. It gives to opaque objects 

 especiaUy an appearance of being inkid with mosaic 

 w^ork composed of myriads of gems of extreme minuteness, 

 and the most vivid prismatic colours ; the higher the 

 power we employ is, the more striking is the phenome- 

 non. Nevertheless I am disposed to think that transpa- 



