ISOPERIMETRICAL PROBLEMS. 



[Being a Friday evening Lecture delivered to the Royal 

 Institution, May I2//?, 1893.] 



Dido, B.C. 800 or 900. 



Horatius Codes, B.C. 508. 



Pappus, Book V., A.D. 390. 



John Bernoulli, A.D. 1700. 



Euler, A.D. 1744. 



Maupertuis (Least Action), b. 1698, d. 1759. 



Lagrange (Calculus of Variations), 1759- 



Hamilton (Actional Equations of Dynamics), 1834. 



Liouville, 1840 to 1860. 



THE first isoperimetrical problem known in 

 history was practically solved by Dido, a clever 

 Phoenician princess, who left her Tyrian home 

 and emigrated to North Africa, with all her 

 property and a large retinue, because her brother 

 Pygmalion murdered her rich uncle and husband 

 Acerbas, and plotted to defraud her of the money 



