The Melted Candy Bar That Cooked the World

Percy Spencer stood before a humming radar set in a Raytheon laboratory, the war in Europe winding down, the Pacific still burning. He reached into his pocket for a peanut-cluster candy bar and found only a sticky smear. The magnetron tube powering the radar had bathed him in microwave radiation, and the chocolate had surrendered to physics.

The Engineer and the Magnetron

Spencer was no ordinary technician. Born in 1894 in Howland, Maine, he was orphaned young, left school at twelve, and taught himself trigonometry, calculus, chemistry, and physics while working in a spool mill and later as a Navy radio operator. By 1925 he had joined the American Appliance Company — soon renamed Raytheon Manufacturing Company — where his intuition for vacuum tubes made him indispensable. During World War II, Spencer solved the magnetron production bottleneck that had limited output to seventeen tubes a day. He devised a stamping method, pressing thin copper cross-sections like cookie cutters and stacking them, lifting daily production to 2,600. By 1945 Raytheon was supplying 80 percent of all Allied magnetrons, the heart of radar systems that hunted U-boats and guided bombers.

The Melting Moment

The candy bar incident was not a passing curiosity. Spencer, ever methodical, sent for popcorn kernels. He held the bag near the magnetron and watched kernels explode into fluffy white clouds. Next came an egg. It cooked so violently it blew up in the face of a watching colleague. Spencer had stumbled on a new way to heat food: microwave radiation agitating water molecules. On October 8, 1945, Raytheon filed a patent for "Method of Treating Foodstuffs," granted in 1950. The company moved fast. By 1947 the first commercial unit, the Radarange, stood nearly six feet tall, weighed 750 pounds, cost $5,000, and required water cooling. It found buyers in restaurants, hospital kitchens, and the galley of the nuclear-powered ship NS Savannah. A coin-operated "Speedy Weeny" vending machine in Grand Central Terminal dispensed microwaved hot dogs to commuters that same year.

From Radarange to Kitchen Counter

For two decades the microwave oven remained an industrial beast. Raytheon licensed the technology to Tappan Stove Company, which introduced a home model in 1955 at $1,295 — still too large and costly. The breakthrough came in 1965 when Raytheon acquired Amana Refrigeration, gaining the manufacturing muscle and distribution channels to shrink the machine. In 1967 the Amana Radarange hit the market: a countertop unit priced at $495. It was smaller, air-cooled, and finally within reach of middle-class families. Sales accelerated through the 1970s as dual-income households sought time-saving appliances. By 1975 microwave ovens outsold gas ranges. Today over 90 percent of U.S. households own one.

Spencer received a one-dollar gratuity for the patent — standard company practice — but rose to senior vice president and board member, holding more than 100 patents before his death in 1970. The microwave oven remains the most ubiquitous consumer product ever born from defense research, a testament to a self-taught engineer who paid attention when his lunch melted.

This is one episode in a much longer story. For the full account of the history of Raytheon, read “Raytheon Co.” by Stephanie Ellis on MixCache.com.