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Monday, September 28, 2015

Exceptional American of the day: Percy Spencer, invented the microwave oven

MIT's Radiation Laboratory conducted the most important technological research in World War II outside the Manhattan Project. Well-credentialed scientists worked alongside military officers and industrialists to develop jet aircraft, submarine detection devices, gun directors, and radar. But to make verything work, the project needed Percy Spencer, a farm boy from Howland, Maine, who dropped out of school in elementary school. Self-educated in trigonometry, calculus, chemistry, physics, and metallurgy, Spencer was Raytheon's ace-in-the-hole, and the main reason the company landed a defense contract in 1939. Spencer headed its power tube division. Magnetrons were the core mechanism in early radar. Raytheon produced 17 of them a day. Spencer upped production to 2,600 magnetrons a day. Those magnetrons would render Hitler's submarine fleet useless.

And then the war ended, and Spencer invented the microwave oven.

Born on July 19, 1894, Percy Lebaron Spencer was 18 months old when his father died. His mother split and an aunt and uncle raised him. When he was seven, his uncle died. He went to work at the local spool factory at 12. The owner decided to electrify the factory. This was a first for Howland, a town in the middle of Maine. Spencer read all he could about electricity. The owner hired him as one of three installers.

He was 16.

At 18, wireless radio caught his attention. The sinking of the Titanic a few months earlier popularized the technology. Spencer joined the Navy and became a radio technician. At night, while standing watch, he read all he could on the subject. His was an inquisitive mind. Don Murray of Reader's Digest wrote about him in 1958.

"Percy Spencer is the nosiest man I have ever known. Now 63, he still has an intense, small boy's compulsion to explore every wonder in the world around him. The results of his relentless curiosity have touched the lives of each of us," Murray wrote.

"Recently I walked into his office at the Raytheon Manufacturing in Waltham, Massachusetts -- an office befitting the senior vice-president of one of the nation's largest electronic' manufacturers. 'Hi, Don,' the stocky, shirt-sleeved Down-Easter shouted from behind his desk. 'Where'd you get the shoes?'

"The moccasin-type shoes weren't that different, but I knew Percy. Were the shoes comfortable, he asked. Would they wear? Why were they stitched like that? In a minute I had one shoe off, so that he could examine it. He wanted to know just how it was made."

That is how you learn, by asking. And his acquisition of answers -- his knowledge -- is why Vannevar Bush, a co-founder of Raytheon, hired Spencer as chief of its ray tubes division in 1925, a year after his hitch in the Navy ended. Bush was a Tufts College graduate who was an engineer and inventor. Spencer's lack of formal credentials did not matter in America. Ability mattered. He earned the respect of physicists.

The name of MIT's Radiation Laboratory was a misnomer, as was the Manhattan Project's name, designed to throw off German spies. Raytheon had tremendous faith in Spencer, putting him in charge of 5,000 employees. His ability to re-invent the manufacturing process and boost production helped shorten the war, and saved lives in the process. For his work, the Navy awarded Spencer the Distinguished Public Service Award, its highest award for a civilian.

As the war wound down, Spencer was working around microwaves. People today romance about the discovery being accidental, but the true story was that a scientist made an observation and followed it down the rabbit hole.

His grandson and fellow inventor, Rod Spencer, explained the situation to Business Insider.

"My grandfather was watching a microwave testing rig, and he realized that the peanut-cluster bar in his pocket started to melt — it got quite warm," Spencer said. "So he put two and two together and he decided to get some popcorn, so he sent the popcorn in and it started popping all over the place. The next morning, he brought in an egg. One of the engineers who was a little disbelieving in terms of a microwave's ability to cook, just as he was looking over, the egg blew up in his face."

On January 24, 1950, Spencer received the most important of the 120 patents he received in his lifetime, U.S. Patent 2,495,429 for his "Method Of Treating Foodstuffs." The first microwave -- called the Radarange -- was six-foot tall, weighed 750 pounds, and cost $2,000 to $3,000. Restaurants bought them and gradually over the years, the microwave oven shrank. By 1974, Americans bought more microwave ovenss than they did gas stoves. No man is the responsible for the sale of more popcorn than Percy Spencer -- not even Orville Redenbacher.

He received no royalties from the patent, however. Raytheon paid him a $2 gratuity. But he never complained. Such is the life of a corporate researcher.

Spencer died on September 8, 1970, in Newton, Massachusetts, at age 76. No doubt he had plenty of questions for St. Peter.


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  1. I read that the microwave tube was engendered by a question on radar: how much power would it take to boil a specific amount of water at a distance of X? In other words, kind of a death ray. As I recall, they couldn't do that during the war.

    " Spencer upped production to 2,600 magnetrons a day. Those magnetrons would render Hitler's submarine fleet useless." HOW did they do that? Wikipedia doesn't say.

    1. Airborne and ship-borne radar; submarines at the time were mainly diesel/electric powered; underwater they had to run on batteries (the Germans had some experimental subs powered by hydrogen peroxide which could stay down longer, but they were too late to change the outcome), which they charged while running diesels on the surface (or later with snorkels). This meant that they could not stay underwater for more than 12 hours or so at a time before the air became unbreathable to the crew and they had to surface or at least poke the snorkel up for air; the radars made possible by the magnetron were both sensitive enough to identify either the surfaced submarine, or just the snorkel, and small enough to be carried on aircraft which could also carry enough fuel to patrol the whole Atlantic when working together. This meant that the U-boats were extremely vulnerable about half the time they were at sea (later in the war, after these radars were introduced); and in the end I believe they suffered approximately a 75% loss ratio over the course of the whole war.