Monday, 20 October 2014

History of the Microwave Oven

It has been a while since I have done o history of everyday items. So I thought I would kick things off again with an item we all use the good old Microwave.


Percy Spencer
The man was Percy Spencer.  At the age of just 18 months old, Spencer’s father died and his mother soon left him to his aunt and uncle.  His uncle then died when Spencer was just seven years old.  Spencer subsequently left grammar school and, at the age of 12, began working from sunup to sundown at a spool mill, which he continued to do until he was 16 years old.  At this time, he heard about a nearby paper mill that was “electrifying”, which intrigued him.  Given that few in his town, a remote community in Maine, knew much of anything about electricity, he began learning what he could about it and managed to become one of three people who were hired to install electricity in the plant, despite having never received any formal training in electrical engineering nor even finishing grammar school.

At the age of 18, Spencer decided to join the U.S. navy after becoming interested in wireless communications directly following learning about the wireless operators aboard the Titanic when it sank.  While with the navy, he made himself an expert on radio technology: “I just got hold of a lot of textbooks and taught myself while I was standing watch at night.”  He also subsequently taught himself: trigonometry, calculus, chemistry, physics, and metallurgy, among other subjects.

Fast-forward to 1939 where Spencer, now one of the world’s leading experts in radar tube design, was working at Raytheon as the head of the power tube division.  Largely due to his reputation and expertise, Spencer managed to help Raytheon win a government contract to develop and produce combat radar equipment for M.I.T.’s Radiation Laboratory.  This was of huge importance to the Allies and became the military’s second highest priority project during WWII, behind the Manhattan Project.  It also saw Spencer’s staff rise from 15 employees to 5000 over the course of the next few years.

World War II Radar
One day, while Spencer was working on building magnetrons for radar sets,  he was standing in front of an active radar set when he noticed the candy bar he had in his pocket melted.  Spencer wasn’t the first to notice something like this with radars, but he was the first to investigate it.  He and some other colleagues then began trying to heat other food objects to see if a similar heating effect could be observed.  The first one they heated intentionally was popcorn kernels, which became the world’s first microwaved popcorn.  Spencer then decided to try to heat an egg.  He got a kettle and cut a hole in the side, then put the whole egg in the kettle and positioned the magnetron to direct the microwaves into the hole.  The result was that the egg exploding in the face of one of his co-workers, who was looking in the kettle as the egg exploded.

Spencer then created what we might call the first true microwave oven by attaching a high density electromagnetic field generator to an enclosed metal box.  The magnetron would then shoot into the metal box, so that the electromagnetic waves would have no way to escape, which would allow for more controlled and safe experimentation.  He then placed various food items in the box and monitored their temperature to observe the effect.

Early Radarange Microwave Oven
The company Spencer was working for, Raytheon, then filed a patent on October 8, 1945 for a microwave cooking oven, eventually named the Radarange.  This first commercially produced microwave oven was about 6 feet tall and weighed around 750 pounds.  The price tag on these units was about $5000 a piece.  It wasn’t until 1967 that the first microwave oven that was both relatively affordable ($495) and reasonably sized (counter-top model) became available.

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