MEMORANDA. 87 



plexitj" of my assertion, that light cannot be totally reflected 

 either externally or internally from refracting bodies with 

 parallel sides, when this is a well-known and simple optical 

 fact, yet Mr. Rainey again states that the total reflection he 

 alludes to " is supposed to be from one surface only, namely, 

 from that on which the rays are incident?" 



I have stated that the undulatory theory of light has very 

 little or nothing to do with the illumination of microscopic 

 objects. Mr, Rainey has cleverly turned these four short 

 words, and assumed that I, with great presumption, have 

 ventured to deny the undulatory theory being a correct one, 

 and then proceeds to argue and defend the case as if I had 

 really done so. My meaning (which will be easily under- 

 stood by referring to my paper) was simply this. — When we 

 view a house, a tree, or a distant landscape, I think that it 

 will be admitted that there is no occasion to refer to the un- 

 dulatory theory to account for their visibility. The same 

 reasoning may also be applied to objects of minute size, as the 

 point of a needle, fibres of a piece of textile fabric. All these 

 conditions are still in existence when a magnifying lens is 

 used, which in effect merely serves to shorten the focus of the 

 eye. I cannot see the utility of attempting to endow minute 

 objects with exclusive properties when under the microscope ; 

 their illumination and visibility are simply a question of quality 

 and direction of light, the same as in all ordinary cases, 



Mr. Rainey will, I trust, pardon me for stating that I have 

 not " invented any new theories" to explain the action of my 

 parabolic condenser, for, to use his own words, " these facts 

 allow of an easy and obvious explanation upon long- esta- 

 blished principles." The whole of this implied theory rests 

 upon my ^making use of the term " radiated light." If Mr. 

 Rainey will distinctly contradict the fact, that an illuminated 

 atom does in reality radiate light in all directions, I shall be 

 better able to answer the question. 



I must remonstrate against Mr. Rainey 's assertion that I 

 myself " evince great dissatisfaction with the term radiated 

 light." This refers to a note at the end of my paper, stating 

 that I had adopted the term becavise it was descriptive and 

 convenient, though perhaps not philosophically correct. Mr. 

 Rainey's application of this remark only serves to show me 

 that this is an admission that I ought not to have made. — F. H, 

 Wenham. 



ivcw Achromaric Condenser. — Having invented a new kind of 

 achromatic condenser of general utility, for all kinds of illu- 

 mination, and finding it much superior to anything of the 



