286 Mr KELLAND, ON THE MOTION OF 



SECTION IV. 



Combination of Vibratory Motion with 3Iotion of' Translation when the 



Forces are repulsive. 



56. In the last Section we were occupied with the interpretation 

 of the equations resulting from supposing the particles attractive, or, 

 at least, the force on any one of the same denomination as would 

 result from this hypothesis. It is possible to conceive that in nature 

 the particles are so mixed and so varied in their properties as to 

 allow the above supposition, at the same time that the total action 

 produced on another system is of the opposite denomination. We 

 ought then to examine the nature of the motion on each supposition 

 separately, and, finally, to combine them. 



57. I should be trespassing beyond the bounds of my subject, 

 were I to proceed to the consideration of the modification which such 

 an hypothesis introduces. 



I shall therefore content myself with a few observations. 



If we examine the equations of motion of the medium acted on 

 by repulsive forces, we find them assume the form 



-d¥ = "^' 



from which we conclude, as before, that there is a vibration in the 

 direction of transmission, and that there is a transfer, the motion of 

 any particle being in the plane of the front of a wave. 



