This painting is number 4 of 6 in the series The Progress of Human Knowledge and Culture, painted for the Meeting Room of the Royal Society of Arts in London. The god Father Thames floats down the river on a shell throne, guided by Londoners and naiads. Mercury, the Roman god of trade, flies overhead and guides the group. In the background we see a sculptural lighthouse/observation deck; however, I’m unable to find anything in the world resembling it so I conclude that Barry conjured it up.
In order to secure the commission, Barry offered to do the series for the cost of paint and materials alone, hoping that it would improve his standing in the art community at the time, for he had fallen out with many patrons and fellow artists. When he didn’t get the fanfare he had hoped for, he began writing articles in the press criticizing the Royal Academy (of which he was a member) and became the first to be expelled from the Academy.