250,000 Amperes

"When the bell rings, open your mouth, stop up your ears, shut your eyes and you'd better stand up because sparks are not so apt to land in your lap," said the mild-mannered, middle-aged man who was running the show. "Better wear a hat, too, if you have one."

The bell rang. Between two spheres the size of grapefruit leaped an electric flash. The gap was only six inches, but the flash was blinding, the report thunderous. The voltage was not extraordinary (150,000), but the amperage was--250,000. The current used by a 40-watt incandescent bulb is about one-third of an ampere. Two hundred fifty thousand amperes is a greater current than man has ever produced, a greater current than natural lightning.*

Theatre of last week's demonstration was the high-voltage laboratory on the mezzanine floor of General Electric Co.'s testing plant in Pittsfield, Mass. Ninety-six pyranol-filled capacitators (condensers) were mounted on insulators and ranged three deep in a hollow square. Each row of three capacitators was connected in series, and the inside, middle and outside banks of 32 each were hooked up in parallel. Heavy copper straps converged like spider webs from the square to each of the two spheres in the centre. Ordinary 110-volt, 60-cycle current was stepped up by transformers to 75,000 volts, increased by rectifier tubes to 150,000. Half a minute is required to charge the capacitators. The discharge is accomplished in .000008 sec.

Again & again the warning bell rang. Again & again the lightning produced remarkable effects on objects exposed in its brief path.

A piece of heavy copper wire vaporized into thin air.

The handle of a silver-plated spoon vanished in a shower of sparks.

An insulator a half-inch thick flew into pieces. G.E. men at Pittsfield have been puttering with artificial lightning for 20 years. They have produced 10,000,000 volts (at comparatively low amperage) in a single discharge. Karl Boyer McEachron, 44, designer of the high-amperage apparatus which he demonstrated last week, has been at Pittsfield for twelve years. His spectacular experiments are useful for testing purposes, for studying the destructive effects of natural lightning and means of combating them. When he is not in the laboratory he troops up & down the country lecturing on lightning.

For protecting rural homes and buildings, Mr. McEachron declares a good lightning rod is effective 99 times in 100. In use since Benjamin Franklin's time, lightning rods and the glib agents who sold them were long in disfavor with farmers because so many rod-equipped structures were struck by bolts and burned. But this was found due in almost every case to faulty installation. Nine-tenths of the deaths caused by lightning in the U. S. (some 50 per year) occur in the country. Cities are much safer because big buildings, with steel frames acting as lightning rods, are not only invulnerable themselves but protect a considerable adjacent area.

*The average lightning bolt has an amperage of some 100,000, a voltage of some 100,000,000. Amperage is the amount of current, voltage the pressure that drives it.

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