The “Dew-bow.”

Abstract

ON Wednesday and Thursday, November 4 and 5, fogs prevailed in this district and brought by mild winds great quantities of carbonaceous dust from over the town, which covered the surface of the top pond in Vernon Park with a dry film. On the morning of Friday, November 6, hoar frost covered the grass and walks; the film of dust on the pond was covered with a glistening coat of minute watery globules. At 11.20, standing with my back to the sun, I noticed a bright streak of light on the surface of the water, and on moving a few feet further saw that it was split up into the colours of the prismatic spectrum, and presented the appearance of the rainbow, as it appeared curved. There were two spectra, one fainter than the other. The phenomenon was visible for more than four hours, and I directed the attention of several gentlemen to it. In November, 1885, Mr. Thomas Kay, Moorfield, Stockport, saw a similar phenomenon on Lake Windermere, and published the observation. The things necessary to produce it appear to be:—(1) a dry film of dust on surface of water; (2) a layer of fine globules of moisture on the film; (3) a dead calm, that the globules be not shaken into coalescence; (4) the sun shining brightly at a low angle through a clear atmosphere.