Roar & Squiggle

It was snowing on the northern peninsula of Michigan one afternoon last week. At the vast deserted quarries of Inland Lime & Stone Co., 8 mi. from Manistique, a small group of men--Army & Navy observers, men from the Bureau of Mines and the Coast & Geodetic Survey, quarrymen, photographers -- huddled under a line of steel freight cars. No other humans should have been within a mile of them. The occasion was dangerous. The military men said that during a heavy explosion it was best to stand on one's toes with the mouth open. The concussion then had less effect on the ears. Others opined that it was just as well to lie stretched out on one's stomach.

As 3 p. m. C. S. T. approached, the men under the steel cars became attentive. Attentive also to what was going to happen at the quarries were scientists tending earthquake recorders at Madison, Wis., Ann Arbor, East Lansing, St. Louis, Buffalo, New York City, Washington. Chronometers of everyone interested were set to check with a radioed time signal from the Naval Observatory at Washington.

At 3 p. m., Lieut. Edwin J. Brown of the Coast & Geodetic Survey grasped the switch of an electrical device under his freight-car shelter. From the device ran 7 mi. of wire, which dipped into a mile-long line of steel cases buried in the limestone quarries. There were 5,000 steel cartridges. They contained altogether 220 tons of dynamite. Lieut. Brown at 3:02 p. m. was to set off the mightiest single controlled blast that man has ever dealt with.

For the quarrymen the blast would churn up 1,125,000 tons of limestone, sufficient to supply the blast furnaces of Inland Steel Co. (which controls the stone company) one year. For seismologists the blast would show how much of an effect a 220-ton jolt had on the 6.6 x 1021-ton earth. The knowledge would give them something precise by which to measure the forces underlying all earthquakes.

At 3:02 p. m. the Naval Observatory signaled "Go." Lieut. Brown pulled his switch. A strip of rocky earth a mile long by 200 ft. wide heaved up slowly, settled with roar and dust. At the distant earthquake observatories, the seismographs registered faint squiggles. Thus man knew that he had shaken the earth, made it quiver, trifling though that quiver was.

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