Democratic Sentinel, Volume 17, Number 42, Rensselaer, Jasper County, 3 November 1893 — Exposure to Sunshine. [ARTICLE]

Exposure to Sunshine.

Apropos of the effect of exposure to sunshine destroying microbes, Mrs. Percy Frankiand, in Longmans’, notes the interesting fact that exact experiments conducted in the Lake of Geneva to ascertain by means of photographic plates the depths to which the sun’s rays penetrate, showed that they did not reach beyond 553 feet, at which depth the intensity of the light is equal to that which is ordinarily observed on a clear but moonless night.