7,000,000 Volts

After sundown one day last week an airplane slipped in to a landing at "Round Hill," the South Dartmouth, Mass, estate of Hetty Green's stamp-collecting, air-minded son, Colonel Edward Howland Robinson Green. It taxied up close to a capacious airship dock, and out of it stepped President Karl Taylor Compton and Vice President Vannevar Bush of Massachusetts Institute of Technology.

The two men strode into the cavernous metal hangar in which was no dirigible but M. I. T.'s giant electrostatic generator (TIME, March 7, 1932). There they joined newsmen and M. I. T. engineers and miscellaneous scientists. In the gloom loomed the generator-- two gleaming 15-ft. hollow aluminum balls, each atop a 25-ft. column of textolite, each column mounted on a massive four-wheel truck. The two trucks were on a single track which ran the length of the hangar and beyond. Small manholes opened into both aluminum balls which were rigged up inside as compact laboratories.

After a quick inspection Dr. Compton boomed: "Perhaps not all of you understand that this is the first test of the Van de Graaff electrostatic generator as a complete machine. . . . Up to the time Dr. Van de Graaff built his small laboratory model [at Princeton] which developed more than 1,000,000 volts [TIME, Nov. 16, 1931], the highest direct current ever attained by man was about 800,000 volts. With this big generator we hope tonight to reach several million volts. ..."

Dr. Compton turned to a dark, heavy-chinned young man standing quietly at his side. Robert J. Van de Graaff was born in Alabama 32 years ago, won a Rhodes scholarship, became a National Research Fellow at Princeton, designed and built his big generator as an M. I. T. research associate.

"Are you ready to start, Dr. Van de Graaff?" "I believe everything is ready, Dr. Compton."

A Van de Graaff staff member clambered up a ladder into the ball which was to serve as the positive terminal. Into the negative ball climbed another, followed by a spunky newshawk. Two more staff men went to shielded control boards at the foot of each column. Builder Van de Graaff barked instructions.

"Remove the ladders! . . . All ready in the spheres? Lights out! Power on!"

A rising hum filled the still darkness of the hangar. Small motors were driving endless paper belts which, riding on pulleys and whizzing invisibly up & down within the columns, picked up electrical charges from the exciters below and piled them up on the balls above. One belt carried negative electricity, the other positive. In the galvanized atmosphere the hair of the watchers stood straight up, their elbows tingled, their fingertips glowed. Luminous halos began to fringe the balls.

Abruptly a thunderclap resounded as a blinding arc leaped from ball to ball. Other flashes followed in a steady crackling punctuated by deafening reports. The air was pungent with ozone. Through the din Dr. Van de Graaff bellowed:

"Widen the gap!"

Staff men pumping ratchet levers jacked the trucks slowly apart until the air gap between the fulminating balls approached 40 ft. Blue, green, violet and lavender lightning lapped hungrily around the bases of the columns, licked the steel roof-beams overhead, searched the walls of the hangar, crashed from ball to ball. At last the designer cried:

"Stand by! Power off! Lights! Lights!"

Amid warm congratulations. Dr. Van de Graaff announced calmly that the voltage reached was about 7,000,000--a record for man-made lightning.* But to him the test, though spectacular and successful, was simply another step toward a final objective. If unfavorable weather had not forced him to hold his show indoors, he would have had the trucks moved outside where, with none of the stored electricity sparking into hangar walls and beams, he could have counted on 10,000,000 volts.

Dr. Van de Graaff knew, moreover, that a vitally important part of his huge contraption, as a scientific instrument, was a 40-ft.-long vacuum tube made of laminated paper. Still unfinished and untested last week, this tube is to bridge the gap between the balls, serve as a channel for the 10,000,000 volts which Dr. Van de Graaff expects to produce. At one end of the tube swarms of protons will be released. The high voltage will whip these particles down the tube against a target at the other end. Dr. Van de Graaff hopes that these bullets will disrupt the nuclei of the target's stable atoms in such comparatively copious numbers/- that he will 1) learn more about the ultimate constitution of matter; 2) produce superpowerful x-rays: 3) glimpse a clue toward utilization of atomic energy.

* The voltage nf natural lightning rises above 100,000,000, with an air leap of more than 1,000 ft.

/-The University of California's Professor Ernest Orlando Lawrence has accomplished atomic disintegration by whirling his bullets (deutons, or heavy hydrogen nuclei) with a magnet as fast as 2,000,000 volts would have driven them (TIME, July 3).

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