Curiosities of Science. 51 



he intently watches floating about till they burst. He is doubtless," she 

 added, ' ' now at his favourite amusement, for it is a fine day ; do come 

 and look at him." The gentleman smiled, and they went upstairs ; 

 when, after looking through the staircase- window into the adjoining 

 court-yard, he turned and said : " My dear madam, the person whom 

 you suppose to be a poor lunatic is no other than the great Sir Isaac 

 Newton studying the refraction of light upon thin plates; a phenomenon 

 which is beautifully exhibited on the surface of a common soap-bubble." 



LIGHT FROM QUARTZ. 



Among natural phenomena (says Sir David Brewster) illus- 

 trative of the colours of thin plates, we find none more remark- 

 able than one exhibited by the fracture of a large crystal of 

 quartz of a smoky colour, and about two and a quarter inches 

 in diameter. The surface of fracture, in place of being a face 

 or cleavage, or irregularly conchoidal, as we have sometimes 

 seen it, was filamentous, like a surface of velvet, and consisted 

 of short fibres, so small as to be incapable of reflecting light. 

 Their size could not have been greater than the third of the 

 millionth part of an inch, or one-fourth of the thinnest part of 

 the soap-bubble when it exhibits the black spot where it bursts. 



CAN THE CAT SEE IN THE DARK ? 



No, in all probability, says the reader; but the opposite 

 popular belief is supported by eminent naturalists. 



Buffon says : " The eyes of the cat shine in the dark somewhat like 

 diamonds, which throw out during the night the light with which they 

 were in a manner impregnated during the day." 



Valmont de Bamare says : " The pupil of the cat is during the night 

 still deeply imbued with the light of the day ;" and again, " the eyes of 

 the cat are during the night so imbued with light that they then appear 

 very shining and luminous." 



Spallanzani says : " The eyes of cats, polecats, and several other ani- 

 mals, shine in the dark like two small tapers ;" and he adds that this 

 light is phosphoric. 



Treviranus says: ' ' The eyes of the cat shine where no rays of light 

 penetrate ; and the light must in many, if not in all, cases proceed from 

 the eye itself." 



Now, that the eyes of the cat do shine in the dark is to a 

 certain extent true : but we have to inquire whether by dark 

 is meant the entire absence of light ; and it will be found that 

 the solution of this question will dispose of several assertions 

 and theories which have for centuries perplexed the subject. 



Dr. Karl Ludwig Esser has published in Karsten's Archives 

 the results of an experimental inquiry on the luminous appear- 

 ance of the eyes of the cat and other animals, carefully distin- 

 guishing such as evolve light from those which only reflect it. 

 Having brought a cat into a half- darkened room, he observed 

 from a certain direction that the cat's eyes, when opposite the 



