RHEOMETRY. 341 



V s 

 the case requires. We have then s = ~ ; or since y* = 2 px, we 



have * = = ; and showing that the area in question is 



3p 3 



two-thirds of the product of the abscissa and ordinate by which the 

 area is included. Such are the beautiful applications of the differ- 

 ential and integral calculus. 



