dauphin

dauphin The eldest son of the king of France. Under the (w) and (w) dynasties, the Dauphin of France, generally shortened to Dauphin, was heir apparent to the throne of France. The title derived from the main title of the Dauphin, Dauphin of Viennois.
(sense) An eldest son.
(RQ:Chmbrs YngrSt)

"I wish we were back in Tenth Street. But so many children came(..)and the Tenth Street house wasn't half big enough; and a dreadful speculative builder built this house and persuaded Austin to buy it. Oh, dear, and here we are among the rich and great; and the steel kings and copper kings and oil kings and their heirs and dauphins.(nb..)"