When the US Navy fired its biggest guns in the Second World War, the gunpowder went into the breech in a bag of pure silk, and nothing invented since has been allowed to replace it. A battleship's 16-inch gun does not use a brass cartridge. The shell goes in first, and behind it the crew load several bags of powder, each the size of a sack of flour. The bag has one job. It must hold the charge together until the moment of firing and then disappear entirely, leaving nothing behind in the barrel. Any scrap that survives the blast is a smouldering ember in a chamber about to receive the next charge. A fragment of cloth left in the breech has killed gun crews. Silk burns clean. It is a protein, like hair, and in the flash of the charge it turns to a puff of ash and gas and is gone. Nothing else did that. Cotton left residue. The new nylon melted into a sticky bead that stayed in the chamber. So in 1941, when Japan cut off the silk, the Navy claimed every ounce in the country for its powder bags and parachutes, and silk stockings vanished from the shops overnight. When the women of America handed in their old stockings in the great collection drives of 1942, the silk ones went to the fleet to be sewn into powder bags. The battleships are museums now. But the guns on today's warships still fire charges in bags, and the bag is still spun by a caterpillar, because 80 years of chemistry has not produced a fabric that burns to nothing. The same fibre that could not be trusted to hold a plastic bead in a gun barrel is the one that was melting into sailors' skin on the Sheffield. The Navy had the answer in its own magazine.

In 1893 a Norwegian scientist deliberately froze his ship into the Arctic ice, let it drift for three years, and lost not a single man to scurvy or anything else. Then he walked off it and spent nine months in a hole in the ground eating bear. Fridtjof Nansen was thirty-two, a zoologist with a doctorate on the nervous system of a worm. His theory was that the polar current would carry a ship across the top of the world if the ship was built not to be crushed. He built one. He called it the Fram, took twelve men, and sailed into the pack. For three years they lived in the dark and the cold with no fresh food arriving from anywhere. On every previous expedition that had meant scurvy, the disease that had killed more sailors than the sea. Nansen's crew had none. They shot polar bear and seal, and ate the meat fresh and barely cooked, as the Inuit did. The doctor on board had almost nothing to do. In 1895 Nansen and one companion left the ship on skis to make for the Pole. They got further north than any human had been, turned back, and were caught by winter on an empty island. They built a hut of stones and walrus hide, and for nine months they ate bear meat and walrus blubber and nothing else. No vegetable, no grain, no fruit. They came out in the spring fatter than they went in. Then they walked home. Nansen went on to win the Nobel Peace Prize, and lived to 68. Every schoolchild is taught that a diet without vegetables will rot you from the inside. Two men spent a winter underground on nothing but fat and meat and came out fit to walk across the Arctic, and that was 130 years ago.

The jacket that kept the pilots of the Battle of Britain alive was designed by a Hollywood stuntman, and it was a sheep turned inside out. Leslie Irvin grew up in Los Angeles jumping out of balloons for the cameras. In 1919 he became the first man to leap from an aeroplane and open a parachute by hand in free fall. He broke his ankle on landing and started a company on the strength of it. In 1926 he opened a factory in Letchworth, in Hertfordshire. His parachutes were silk. Anyone whose life was saved by one was sent a small gold pin in the shape of a caterpillar, after the creature that had spun the canopy. Then he turned to the other thing that was killing airmen. Aircraft were climbing higher every year, and the cockpits had no heating. At 30,000 feet it is 45 degrees below zero. A pilot's hands stopped working. He could not think. Irvin's answer was approved by the Air Ministry in 1932. Whole sheepskins, the fleece left on and turned inwards, the leather out to the wind. He insisted on the most supple skins, because a man in a Spitfire can barely move his shoulders as it is. In the summer of 1940 that jacket was hanging on a hook at every fighter station in the south of England. The bell went, the pilot pulled it on and ran. Twenty minutes later he was five miles up with no heater, fighting for his country in a sheep. By 1945 more than 34,000 airmen were wearing the caterpillar pin. So the Few went up wrapped in a fleece and came down under a silkworm. The Spitfire gets the statues.