Possible Clues:

• Artist showing power of current with his water
• French painter
• French artist, dispensing with frame, struck gold
• Artist showing some power over water at Giverny
• Painter of some power expressed surprise loudly
• Artist uses power provided by water in France
• Jean-Antoine -, French painter
• French painter's response, say, to summons from Wooster?
• Jean-Antoine -, seventeenth to eighteenth century French rococo painter
• He worked with steam and water to become a painter