A president with no bite
QUESTION Did George Washington have false teeth made of wood?
The first U.S. president’s dentures, mounted between diminutive brass posts and suspended in a clear tube, are a popular curiosity in the museum at his Mount Vernon estate in Virginia. But they are not made of wood.
George Washington had dental problems early in life, probably due to suffering multiple illnesses — he survived smallpox, malaria, TB, and many infections and abscesses. Tooth decay was exacerbated by the harsh drugs used to treat the diseases, and by the abrasive dental treatments of the time.
he had his first tooth pulled aged 24 and from then on continued to lose teeth. By the time he was sworn in as president in 1789, aged 57, he had just one tooth left. From 1790 until his death in 1799, Washington wore a full set of dentures.
Rather than the simple wooden pegs of legend, they were the cutting edge of 18th-century dental practice, supplied by Dr John Greenwood, New York City’s premier craftsman dentist. he made and repaired several of Washington’s dentures and had a lengthy correspondence with the president.
The technological sophistication is apparent from the only complete set of Washington’s dentures to survive. They consisted of two cast lead bases that fitted between the upper and lower jaws. each tooth had a hole drilled through it so it could be threaded onto a brass wire and attached to the base. The bases were connected by circular steel springs that allowed the dentures to move up and down with the mouth.
The lower set consisted of human teeth as well as false teeth made from cow’s teeth and ivory; the upper set were reshaped horse’s teeth.
Dental treatises of the time recommended the use of ‘sea horse’s teeth’ (hippopotamus tusks) as well as elephant, ox and calf teeth. human teeth used in dentures were extracted from dead bodies or even from the living.
There is a story that some of Washington’s false teeth had been extracted from slaves. There is no evidence for this, although it’s possible he bought teeth from slaves. While it may seem gruesome, selling teeth to dentists was once a common means of making money.
Denise Avery, Bristol.
QUESTION Who developed the proximity fuse for anti-aircraft artillery?
The proximity fuse was a crucial innovation during World War II.
The project was started by military researchers at the Telecommunications Research establishment in Worth Matravers, Dorset, led by Samuel C. Curran. however, it was completed by Section T, led by physicist Merle A. Tuve, at The Johns hopkins University Applied Physics Lab in Maryland in the U.S.
The device that controls when a shell, rocket or bomb explodes is called the fuse and is in the tip of the weapon. At the start of the war there were only direct contact fuses, which worked when there was a direct hit. They weren’t much use.
During the early German air raids on Britain, an anti-aircraft gunner reported that shooting down an aircraft in the night sky was ‘akin to hitting a fly in a darkened room with a peashooter’. A conservative estimate suggested it took 1,000 shells to bring down an aircraft. Variable time fuses halved this. They triggered a timer when the shell was fired, which allowed gunners to explode the weapons at a specific altitude.
Curran and his team realised that what was needed was a way for the shells to sense the aircraft and detonate when they were close enough. The plan was to insert a tiny transmitter in the fuse that would emit a constant radio signal. This would reflect off any aircraft that came in range. The reflected radio waves would be picked up by the body of the fuse, which also served as the antenna.
The difference between this and the transmitted signal created a beat frequency, which increased as the fuse got closer to the target. This was amplified, filtered and when it reached a pre-set amplitude, triggered an electronic switch, the thyratron. This started the detonation process 25ft to 75ft from the target, before showering it with shrapnel.
There were serious problems to overcome. The acceleration forces experienced on firing the shells were in the order of 20,000 G-force. To keep the projectile on a stable course, the shells were fired along a rifle barrel that imparted a spin of up to 30,000 revs per minute. These large centrifugal forces wouldn’t be a problem for the solid-state transistors of today, but back then all they had were large, delicate glass vacuum tubes.
The scientists at Johns hopkins proposed a solution to the problem — a fuse ten times smaller, containing a rugged vacuum tube developed from versions fitted to hearing-aid amplifiers.
The top-secret invention was hugely important in the latter stages of the war. It was used against Japanese Kamikaze attacks in the Pacific, in radar-controlled anti-aircraft batteries that neutralised the German V-1 attacks on Britain, and in artillery shells fired against German infantry at the Battle of the Bulge, which changed the tactics of land warfare.
A. L. Short, Royal Leamington Spa, Warks.
QUESTION In the U.S., do you have the right to one phone call if arrested?
IN The U.S., the number of phone calls you can make if arrested varies from as many as you want to none, depending on the severity and location of the crime and how you act when arrested.
Thanks to the Sixth Amendment, you are entitled to legal counsel, so must be able to contact someone upon arrest. Nevada state law stipulates: ‘Any person arrested has the right to make a reasonable number of completed telephone calls from the police station... no later than three hours after the arrest.’
It’s different in Britain. You’re not explicitly entitled to a phone call, but are entitled to inform someone of your detention. The call is usually made by the duty sergeant on your behalf.
James Cohen, London E10.
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