WEST OF ENGLAND JOURNAL 



B(go[iQ^@[i /^m© toTHKATtyiKo 



No. IV. OCTOBER, 1835. Vol. I. 



PART I.— SCIENCE. 



REFLECTION AND REFRACTION OF LIGHT, 



^s explained by Newton, Hmjgens, and a new Theory, in order to form n 



Comparison. 



BY THOMAS EXLEY, A. M. 



( Concluded from page 148.J 



14. The Huygenian theory makes the phaenomena of light to depend 

 on the vibrations, or displacements of the particles constituting an uni- 

 versal ether, supposed to occupy the interminable regions of space. See 

 art. 6. 



The displacements themselves are considered as exceedingly small, so that 

 neitiier the agitated atoms of the ether, nor those of the exciting bodies, 

 become detached, or change their order among the neighbouring particles. 

 Herschel on Light, art. 568. The vibrations originally excited by the lu- 

 minous body, produce successive waves, which are supposed to follow each 

 other with perfect uniformity, swelling and extending themselves in every 

 direction spherically, while they advance through space, till lost in the 

 infinity of their progress. 



15. The distance between the external and internal surface of a wave is 

 called a pulse or undulation ,: its length is measured from any particular 

 phase in one wave to the same phase in the next succeeding or following 

 one; as for instance, from the greatest condensation or rarefaction to the 

 next greatest condensation or rarefaction ; it is exactly double the length of 

 the Newtonian fits of easy reflection and transmission, as determined by the 

 fine experiments of that prince of philosophers. Thus the length of a 

 wave or pulse for red light, or that least refracted, is about the forty thou- 

 sandth part of an inch, and about the sixty thousandth part of an inch for 

 violet light, which is most refracted. In each wave the particles of ether 



No. 4.— Vol. I. 2d 



