From the September 27, 1930, issue

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After 8 years of preparation, the 50-foot interferometer at the Mt. Wilson Observatory in California has been completed. Francis G. Pease, who used the smaller one, 20 feet in length, designed the new instrument and supervised its construction. The smaller one was attached to the 100-inch reflecting telescope at the observatory, and with it the first star diameters were measured, using a principle worked out originally by Prof. A.A. Michelson, University of Chicago physicist.

Antares, the bright red star in Scorpio, the scorpion, was found to have a diameter of 390,000,000 miles and is the largest yet measured. The new instrument can be used for a number of stars beyond the reach of the old instrument, and it is possible that even larger stars may now be found.

Mr. Pease is shown in our cover illustration as he was recently making final adjustments to the instrument. To his right appears one of the flat mirrors, set at an angle of 45 degrees, which slides along the track. A similar mirror slides along another track that was beside the photographer. These mirrors reflect the light from the star to two other mirrors in the center, thence it is reflected to a 36-inch concave mirror below, which brings the light to a focus.

Under proper conditions, when looking through the eyepiece, the image shows a series of light and dark bands, called “interference fringes.” If the star is sufficiently large, these can be made to disappear by moving the outer mirrors, and from their distance when this happens the star’s diameter can be computed. All the motions of the instrument are done by electric motors, controlled from the switchboard seen below the flat mirror.


The structure of a star is something like that of an egg–a dense yolk in the center, surrounded by lighter material. This is the new theory proposed by E.A. Milne, Rouse Ball professor of mathematics at Oxford University, in a communication to the magazine Nature.

In the “yolk,” the temperatures are far higher than astronomers have previously calculated for the interior of a star, he says. His tentative estimate is 100,000,000,000 degrees, instead of a mere 10,000,000 degrees, a figure generally accepted at present. Furthermore, this nucleus is extremely dense, as great or even greater than a star like the strange companion of Sirius, a pint of whose material weighs 25 tons. Prof. Milne thinks that the density of the yolk may reach the maximum possible for ionized matter, that is, matter in which all the atoms are broken up into separate electrons.


To Tungsten, aluminum, and the other metals formerly laboratory curiosities that have now come into wide commercial use may soon be added beryllium. Before long we may be riding in airplanes made of alloys with this metal as a main constituent, or wearing jewelry made of it alloyed with copper. At the meeting of the American Chemical Society in Cincinnati, Dr. Harold S. Booth, professor of chemistry at Western Reserve University, told how he and Miss Gilberta G. Torrey had discovered a new method for making this metal in the pure metallic form.

Beryllium, which is a chemical element like iron or copper, is the lightest metal that does not corrode when exposed to the air. Dr. Booth declared that he had a piece that remained bright after being exposed to the fumes of his laboratory for years.

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