NOT A NIGHT PICTURE

Though it looks at first glance to be a picture of snow-covered trees, taken at night time, the cover illustration this week is of vegetation full of green foliage, taken with light vibrating too slowly to be visible to the eye, the so-called infra-red rays. Though the eye cannot detect them, these rays can be focused through a lens, over which is placed a screen to cut out the more rapid, and visible rays. Photographic plates can be sensitized so that they record this image, though even at best, and on a bright day, a long time exposure is required.

This photograph was taken by the ingenious American physicist, Prof. Robert Williams Wood, of Johns Hopkins University in Baltimore.

IS "CORONIUM" DISGUISED ARGON?

Coronium, the mysterious substance in the sun’s corona that only manifests itself in spectrum photographs made at the time of a total solar eclipse, is probably due to argon, third most abundant gas in the air. This has been found by researches carried on at the Ryerson Physical Laboratory of the University of Chicago by Dr. Ira M. Freeman.

"Coronium" was first found in 1869 when, in the eclipse of that year, astronomers noticed a strange line of green color in the spectrum of the corona. This is the extremely rarefied outer layer of the sun that is visible only when the central disk of the sun is obscured by the moon. Ever since that time physicists have been trying to find the cause of it and a group of unknown lines that were later discovered.

 

EVOLUTION SINCE DARWIN

An example of evolutionary effects in a breed of domestic poultry originally noticed by Darwin, the white-faced Spanish fowl, has gone on evolving rapidly under the guidance of artificial selection, according to a British student of poultry, F. Finn, who writes in Nature. When Darwin knew the breed, Mr. Finn states, its face and the sides of its head were covered with white skin, and its earlobes were prominent and pendulous. This white skin has developed even more extensively during the half-century since Darwin called attention to the birds, and the earlobes have vanished as such, having been merged in a sort of horizontal dewlap that hangs across the cock’s throat.