HMS Vulture's Revolving Wheels of Light, Persian Gulf, 1879

HMS Vulture was a Plover-class wooden gunvessel, launched at Sheerness on 6 November 1869 and posted to the East Indies station in the Persian Gulf. Her commander was J. Eliot Pringle. On the evening of 15 May 1879 she lay at Lat. 26°26′ N, Long. 53°11′ E. The wind was north-west, force 3. The sea was smooth, with a slight swell.

About 9.40 p.m. Pringle noticed something in the water. "Luminous waves or pulsations," he wrote, "moving at great speed and passing under the ship from the south-south-west." He looked east. The appearance was "that of a revolving wheel with centre on that bearing, and whose spokes were illuminated."

He looked west. A similar wheel was turning there too, but in the opposite direction.

He judged the bands to be twenty-five feet broad, with dark intervals of about seventy-five feet between them. They came at seventy-four to seventy-five per minute, giving a speed of roughly eighty-four miles an hour. The light looked homogeneous, lighter than the usual phosphorescence at sea, but not so sparkling. It reached well under the surface. It lit up the white bottoms of the quarter-boats.

By degrees the source of the waves swung from south-south-west to south-east, then to east. In the last five minutes, concentric waves seemed to spread from a spot about 200 yards east. Where they met the parallel waves, they did not cross, but appeared to obliterate each other. The whole display lasted some thirty-five minutes. Pringle called it beautiful and striking.

Pringle wanted a better angle. With the first lieutenant he climbed to the mizen top, fifty feet above the water. From there the wheels came apart.

The luminous waves were really travelling parallel to each other. The rotation seen from the deck, he concluded, came from their high speed and the greater angular motion of the nearer part than the more remote. He added one more detail. The ship had passed through oily-looking fish spawn that evening and the next morning.

Pringle wrote his report at Bahrain on 17 May 1879. The Hydrographer, Captain Frederick Evans, passed it on, and Nature printed it on 24 July 1879. More letters followed in Nature that August, one of them from Edward L. Moss. There was no formal investigation. No one has ever suggested the report was invented.

Pringle's own reading was bioluminescence seen in perspective, and later writers agree that luminous organisms are involved. The exact mechanism is still unknown. In 1960 Kurt Kalle proposed local seaquakes, with wheels formed where circular waves from two sources interfere. That may fit the concentric rings Pringle saw at the end. In 1968 George Verploegh pointed instead to a short, steep swell whose crests may act as cylindrical lenses.

Charles Fort retold the case in The Book of the Damned in 1919, wondering whether it might be a vast luminous wheel under the sea. Ivan T. Sanderson made it standard reading for students of the unidentified submerged object, in Fate in 1964 and in Invisible Residents in 1970. William R. Corliss catalogued it beside a string of similar reports: the Patna in the Persian Gulf in 1880, the Kilwa in 1901, ships in the Strait of Malacca and beyond. A naval commander's careful numbers, and a question the sea has not yet fully answered.