If you can't stand the heat

It's about 137 degrees outside, but who's counting? Wait, I just made that up. It's actually 127. Thank goodness the AC is working. Here's a bit of the history of why that's so.

• In the 2nd century, a Chinese inventor, Ding Huan, devised the rotary fan. As big as six feet across and manually powered, it could cool a whole room. In British India, wealthy homes had a cloth sail called a punkah attached to the ceiling. A servant in another room, the "punkah wallah," would move the fan back and forth by means of a rope and pulleys. These methods, of course, required the poor to get hotter so that the rich might be cooler.

• In 1758, Benjamin Franklin experimented with the rapid evaporation of volatile liquids, such as alcohol and ether, to cool water to a point below freezing. He was able lower the temperature to 7 degrees Fahrenheit from 64. In a letter to a friend, Franklin wrote that the experiment showed that, scaled up, "one may see the possibility of freezing a man to death on a warm summer's day."

• Sixty years later, the great British physicist Michael Faraday demonstrated that one could use mechanical power to compress a volatile substance such as ammonia into a liquid—and then, by allowing it to rapidly evaporate, cool water.

• Soon after, John Gorrie—a young doctor living in Apalachicola, Fla.—had a problem to solve. He knew that patients were more likely to survive an illness in cool weather than in hot. So he rigged up pans full of ice near the ceiling in a hospital room. The ice would cool the air around it and, because cold air is heavier than hot air, would flow downward, over the patient and then out through holes in the room's floor. It was the first effective system of air conditioning.

• But ice was expensive in Apalachicola because it had to be imported by ship from the North, so Gorrie began to experiment with making ice by mechanical means. In 1851, he was granted a patent on a machine that worked on Faraday's principle. He quit medicine to work on perfecting his invention, but when his financial backer died he was unable to carry on and died in poverty in 1855.

Bummer.

• In 1902, Willis Carrier, a young engineer at the Buffalo Forge Company in Buffalo, N.Y., invented the first modern air conditioning, to cool a printing plant. He used a compressor to liquefy ammonia and then evaporated it to cool water. Running the water through coils, he blew air across them, cooling the air and causing it to lose moisture through condensation on the coils. The air was then ducted into the workspace.

• While useful for industrial purposes, Carrier's air-conditioning system was both large and dangerous, as ammonia is very toxic. But by the early 1920s he developed a much more efficient compressor and started using a much safer refrigerant called dielene as the volatile. (DuPont would invent Freon in 1928.)

As with all major inventions, air conditioning has had profound consequences. Washington, D.C., used to be nearly deserted in the summer because of the city's notorious heat and humidity. Today, the government runs year-round. That's not necessarily progress.

New ways of making things

The factory of the past was based on cranking out zillions of identical products, The Economist reports. But the cost of producing much smaller batches of a wider variety, with each product tailored precisely to each customer’s whims, is falling. 

A number of remarkable technologies are converging to let this happen: clever software, novel materials, more dexterous robots, new processes (notably three-dimensional printing) and a whole range of web-based services. 

The old way of making things involved taking lots of parts and screwing or welding them together. Now a product can be designed on a computer and “printed” on a 3D printer, which creates a solid object by building up successive layers of material. The digital design can be tweaked with a few mouseclicks. The 3D printer can run unattended, and can make many things which are too complex for a traditional factory to handle. In time, these amazing machines may be able to make almost anything, anywhere—from your garage to an African village.

The applications of 3D printing are especially mind-boggling. Already, hearing aids and high-tech parts of military jets are being printed in customised shapes. The geography of supply chains will change. An engineer working in the middle of a desert who finds he lacks a certain tool no longer has to have it delivered from the nearest city. He can simply download the design and print it. The days when projects ground to a halt for want of a piece of kit, or when customers complained that they could no longer find spare parts for things they had bought, will one day seem quaint.

Like all revolutions, this one will be disruptive.

Digital technology has already rocked the media and retailing industries, just as cotton mills crushed hand looms and the Model T put farriers out of work. Many people will look at the factories of the future and shudder. They will not be full of grimy machines manned by men in oily overalls. Many will be squeaky clean—and almost deserted. Some carmakers already produce twice as many vehicles per employee as they did only a decade or so ago. Most jobs will not be on the factory floor but in the offices nearby, which will be full of designers, engineers, IT specialists, logistics experts, marketing staff and other professionals. The manufacturing jobs of the future will require more skills. Many dull, repetitive tasks will become obsolete: you no longer need riveters when a product has no rivets.

Read the whole thing. Propping up a failed General Motors looks kinda stupid.