From the August 29, 1931, issue


Throbbing electric generators, the machines that are the heart of the great system supplying light and power to more than 120 millions, are odd and beautiful subjects for the talented photographer. In the picture on the cover, Rittase of Philadelphia has caught the spirit of one of the largest hydroelectric generators.

It is one of the seven 54,000-horsepower units of the Conowingo plant on the Susquehanna River in Maryland. This plant supplies a large share of the industrial load of the Philadelphia district and is designed so that its 378,000-horsepower installed capacity can be increased at the demand of the market.

As large as they are, these generators are not a part of the biggest hydroelectric units in the world. Niagara Falls has such machines of 90,000-horsepower capacity and the Dnieprostroy project now being completed on the Dnieper River in the U.S.S.R. will contain 100,000-horsepower units.


Electrons streaming from the sun may be the cause of our familiar but mysterious blue sky, Dr. Willi M. Cohn of the University of Berlin has concluded as the result of his experiments in which a blue light very similar to that from the sky was produced in the laboratory. Dr. Cohn is doing high-temperature research at the A.D. Little laboratories.

Dr. Cohn experimented in Berlin with cathode rays in a high vacuum, formed in a tube similar to the X-ray tube. He allowed the stream of electrons, which is the cathode ray, to meet larger electrically charged particles of matter, known as ions, which are formed either from a piece of radioactive metal, such as thorium, or from a gas. The blue light appeared where the electrons and the ions came together.


A natural substance 300 times sweeter than cane sugar, rivaling some of the coal-tar products of chemical laboratories, has been shown by two French chemists to consist of a chemical union of common glucose and another compound that has little or no taste. United, they are intensely sweet; divided, they are not even as sweet as ordinary sugar.

The compound bears the chemical name stevioside, because it occurs in a South American plant known to botanists as Stevia. The plant itself was first introduced to the scientific world about the beginning of the present century; it is a close relative of such familiar North American weeds as boneset, Joe-Pye-weed, and the plant that causes occasional outbreaks of milk sickness in the Midwest. After its discovery by Europeans, it rapidly acquired the name of the sweetest plant in the world. A very small piece sufficed to sweeten a cup of coffee or tea.

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