Bigger Air

On the average highway there is room for three motorcars. If drivers would scrap their cars and ride motorcycles instead, room would be made for at least three times as many vehicles.

Similarly with the ether highways of the radio world: the wave-bands assigned to different stations must be spaced across the radio spectrum to avoid overlapping, garbling of messages. Reducing the "width" of the wave-bands would make "more room" on the air.

That was the significance of an invention announced last week in London. If it lives up to its inventor's expectations, "room" may be made on the U. S. air for 3 1/3 times the present number of stations (631); on Britain's air, for three times the present number of stations (20). Long-wave stations must now be spaced at least ten kilocycles apart.

The inventor is Dr. James Robinson, onetime chief of wireless research for the Royal Air Force. He calls his device the stenode radiostat, which briefly means an instrument for binding within sharply defined limits.

Incoming impulses, though closely bordering those of another station (three kilocycles away) are sharply defined in the radiostat. All extraneous impulses are clipped off in a piezoelectric* crystal gate, which is the heart of the invention. Future developments for the invention within sight of Dr. Robinson: increasing cable capacities from 500 words per minute, their present rate, to 20,000 w.p.m.; tremendous expansion of trans-Atlantic telephone service.

Other radio news of last week: reports on the effect of solar eclipse.

Sir Oliver Heaviside and A. E. Kennelly formulated in 1902 their "radio roof" theory: that Earth is surrounded by a sac of ionized ether which acts as a reflector (or conductor) of radio signals. During daytime the sun's light pushes this layer closer to Earth, lessens efficiency of reception. At night the layer rises, reception reaches maximum efficiency.

Best means of testing the Kennelly-Heaviside theory is to experiment during a solar eclipse. This was done in the U. S. last fortnight.

One past student of the phenomenon is John Howard Dellinger, chief of the radio laboratory of the Bureau of Standards who last week made no observations but hoped that others would confirm his work. Chief among confirmers was Herbert Hoover Jr. who studied the effect in California, wrote a story about it for William Randolph Hearst. Substantiating the Kennelly-Heaviside theory, said he: "It was found . . . that radio conditions which ordinarily are associated with darkness became noticeable during ... the eclipse."

* Piezoelectricity (piezo, Greek to press), discovered by the Curies a half-century ago, is generated when pressure is applied to a pyroelectric crystal (one in which a temperature change produces a state of electric polarity). In the piezo effect the amount of electricity freed is proportional to the pressure applied. First pyroclectric crystal discovered: tourmaline.

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