Technology Notes

Recent news of invention and engineering:

>> Going into the gloom of dark cinema houses, people are likely to stumble, bump into others. Ushers with flashlights are nuisances; small lamps placed near the aisle floors illuminate only small areas. American Cyanamid Co. announced what it considers a better idea: aisle rugs treated with fluorescent dyes, bathed by invisible ultraviolet radiation from small tubes. Such rugs glow softly all over, interfere with nothing on the screen. General Electric's House of Magic at the New York World's Fair has a fluorescent aisle rug.

>> For years researchers of Chicago's Swift & Co. hunted for a chemical which would delay the spoiling of lard by oxidation and would protect lard's linoleic constituent, rich in vitamin F. They finally found what they wanted in gum guaiac, made from the sap of the tropical American guaiacum tree. Swift's President John Holmes said that lard treated with tiny amounts of gum guaiac was odorless, bland in flavor.

>> Plaster of Paris absorbs moisture, and the wetter it gets, the lower its electrical resistance. Dr. George John Bouyoucos of Michigan State College made use of this principle in a handy gadget which tells farmers the moisture content of their fields. Blocks of plaster of Paris the size of safety-match boxes are buried with wires leading to the surface. The wetter the soil, the lower the resistance of the buried blocks. Measurements can be taken by merely hooking the surface wires to a Wheatstone bridge, which measures the electrical resistance. By burying a number of plaster blocks at key locations, a farmer can go around at any time and get a moisture map of his land.

>> In neutral but palpitant Sweden, engineers of Ericsson Telephone Co. devised an air-raid alarm which works like a doorbell. The bell can be plugged into an ordinary current outlet in the house. If raiders come, the power plant slightly steps up the voltage in the line, rings the alarm bell in all houses which have one.

>> Rubber which conducts electricity sounds like an anomaly--but such a rubber would be an advantage for airplane and truck tires, for rubber hospital floors. Reason: conducting rubber would continuously discharge static electricity, prevent it from accumulating to the point of spark peril. Static sparks in hospitals have been known to cause anesthetics to explode. In The Rubber Age, Engineer Howard E. Elden of Dunlop Tire & Rubber Corp.

declared that his company has produced a successful conducting rubber. Whereas natural rubber has a resistance of 1,000,000,000,000,000 ohms per cubic centimetre, Dunlop's conducting tire rubber records only 30 ohms per c.c., its cable rubber only ten ohms. On how the rubber is made, Engineer Elden was mum. Dunlop Tire & Rubber Corp. has taken out no patents, for patenting would make the details public, but has begun to market its conducting rubber.

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