330 PROFESSOR KELLAND ON THE THEORETICAL INVESTIGATION OF, &c. 



CONCLUSION. It appears that in all the Problems, the result is one and the 

 same, that the divisor is b \. Hence, we enunciate Huyghens' principle as fol- 

 lows : The vibration at a given point, caused by a given wave, is found by taking the 

 front of the wave, dividing it into an indefinite number of small parts, considering the agi- 

 tation of each of these parts as the origin of a wave whose maximum of vibration, on 

 reaching the point, is equal to the quotient of that at the disturbing point, divided by the 

 product oftlie length of the wave, and the perpendicular from the disturbed point on the 

 front of the wave. 



