tor. HerscheVs Reviewer reineU'ed. 365 



nected with the question the reviewer adds : " Because the 

 rays of li^ht undergo certain flections and modifications in 

 the neighbourhood of bodies near which they pass, it surely 

 does not follow that they are not liable to other modifica- 

 tions at the surfaces of transparent bodies. In fact, these 

 colours are identical with those of the coronae described by 

 Mr. Jordan and other authors." 



The reviewer must have been slumbering when he would 

 have the reader to believe Doctor Herschel had still to learn 

 from him that light may be hable to modifications at the 

 syrfaces of transjiarent bodies ; since the close investigation 

 cm those very modifications makes the sole business of Doc- 

 tor Herschel's essay, from the beginning till very near the 

 end. This hypothesis of the reviewer's inattention is further 

 confirmed by what is immediately added in the conclu- 

 sion of the last quotation. There the originality of the 

 experiment alluded to has wholly escaped him ; for he 

 mentions it as nothing but what had before been lamiliar to 

 Mr. Jordan and other authors. 



But to proceed : The proofs which the author has brought 

 forward against the existence of the fits of easy reflection 

 and easy transmission of light are detailed in the 31st and 

 32d articles of his essay, and may be considered as the 

 most important part of it; as leading on to new views 

 and improvements of Sir Isaac Newton's philosophy of 

 light and colours. 



Let us therefore next see what the reviewer ha? given us 

 about this. The quotation is from the 21th page of The 

 Retrospect. " We do not wish to be considered as stre- 

 nuous defenders of the Newtonian fits of easy transmission 

 and easy reflection ; but we will venture to maintain that 

 Doctor Herschel has advanced no one argument that can 

 have any weight in lessening the probability of their ex- 

 istence." And in fi,ve lines further on, it is added ; " Nor 

 had Doctor Herschel any reason to expect a sensible change 

 in the appearance of the rings, when they were viewed 

 through the wedges of air and glass which he describes, 

 since those wedtres were much too thick to produce any 

 observable colours in while liaht, and for the same reason 

 too thick to produce any perceptible interruptions in the 

 rnigs*j the cflTects of the uiterruptions of two portions of 

 light, differing but very little in refrangibility, being so dif- 

 ferent as to counteract each other." 



Now really in the whole of this, till we come to ihcastC' 

 risk, there is nothing to be found in the form of argument. 

 'I'hal the wedges described by Doctor flerschel were much 



too 



