Many ancient Romans believed that dog sacrifice appeased the rage of Sirius and thus diminished the heat of Summer. The brightest star in the night skies of Summer was Sirius, from the Greek word for “scorcher”. The religionists believed that Sirius was the cause of heat and humidity, so the Romans sacrificed brown dogs to satisfy the anger of the star. Such is one legend about the origins of “dog days”.
Fortunately, we have science and technology to thank for a much more effective technique to use against the discomfort of the season. People can now flick a switch or dial down a thermostat to enable the air conditioning. A/C is so common these days in the West, that most of us take it for granted.
We really should be more thankful for the complicated machinery that brings us the cool air. Air Conditioning Appreciation Days occur during the weekend of US Independence Day. This is the time of year when serious summery heat has settled in to stay awhile. This is the time of year that we seek the comfort and safety of a cool room. Now is the time of year we can easily appreciate the products and services of a $30,000,000,000 industry.
Whether the air conditioning is in an office tower, a home, or a vehicle, the works are basically that of refrigeration, or the moving of heat from one place to another. Artificial refrigeration is a relatively young technology.
History attributes the very first experiments to Scottish professor William Cullen. In 1755, Cullen utilized a primitive pump to cause a partial vacuum over a can of diethyl either. The vacuum caused the chemical to boil. The process absorbed heat from the surrounding air. Cullen’s experiment proved that heat could be transfered from one place to another.
Three years later, chemistry professor John Hadley collaborated with Benjamin Franklin to investigate how evaporation can rapidly cool objects. At the Cambridge University laboratory, the pair validated Cullen’s findings that evaporation of volatile liquids like either and alcohol quickly drop the temperature of objects.
Hadley and Franklin utilized the bulb of a mercury thermometer coated in the liquid, they used a bellows to drive air across the bulb causing the temperature to drop from 18°C down to -14°C. An ice film formed on the thermometer that halted the experiment. Franklin commented, “From this experiment, one may see the possibility of freezing a man to death on a warm summer’s day”.
The next phase happened in 1805 when Oliver Evans designed a closed ether vapor-compression cycle to produce ice. Then, in 1820, the English scientist Michael Faraday perfected the Evans process by using liquefied ammonia under high pressure to create low temperatures. American-British inventor Jacob Perkins went on to build the first working example of a vapor condensing-compression system in the world. Perkins’ invention was designed to work continuously.
The first practical device to use the vapor compression refrigeration technology was built in 1851 by the British journalist, James Harrison, who had emigrated to Australia. His mechanical ice-making machine was then manufactured in 1854 and patented two years later. Harrison’s invention was soon expanded into the meat packing and brewery industries. French and German inventors continued work on the refrigeration process utilizing various chemicals and improved mechanical technology.
In 1841, American doctor and inventor John Gorrie expanded the use of ice enabled cold-rooms to enhance the health of his patients in the hospital. Gorrie continued experimenting with the techniques developed by Michael Faraday. Gorrie wanted to refrigerate hospital rooms by way of Faraday’s theories. Gorrie came close, but the machinery suffered dangerous leakage and circulation failures. Despite his difficulties, Gorrie’s patents were approved in 1851 and he found an investor. Unfortunately, the investor died in 1855 and air-conditioning development went into hibernation for the remainder of the nineteenth century.
In 1902, one year after Willis Carrier finished his Masters Degree in Engineering from Cornell University, Carrier designed the first device to cool and control humidity for an industrial application. The machinery was developed in order to prevent the wrinkling of paper and smudging of ink at a printing plant. The environment was crucial in order to enable the precise alignment needed in four-color printing processes. Carrier had designed a system that blew air over and around artificial refrigeration coils.
The first cooling machines were very large and noisy. Furthermore they frequently leaked toxic chemicals like ammonia, methyl chloride, and propane. The potential for ill-effects and death were ever present. In 1926, Thomas Midgley built an air-conditioner unit that utilized the safer gas, Freon. The lack of toxicity enabled Carrier’s company to launch the limited use of a/c to the public.
As is the case with most technological devices, air-conditioning improved with further advances and improvements in the machinery. Miniaturization and better efficiency allowed a/c to expand beyond industry and movie theatres. By mid-century, air conditioning units were installed in offices, hospitals, and retail stores. Some of the more well -to-do residents had a/c installed in their homes, as well.
Not many years later, window-sized air conditioners were marketed to average consumers.
By the 1970s central air conditioning in homes became more popular as the units evolved simplified, less expensive more efficient technology. Improved variations of Freon allowed for more efficient, smaller condensers and coils. Central a/c began to realistically compete with portable, window-size units. Also, lighter, more efficient car and truck air conditioning was installed into motor vehicles.
In 1994, Freon was determined to contribute to ozone depletion in the atmosphere and was banned in many nations. More environmentally friendly coolants like “R134a” were substituted in place of Freon.
The road to indoor climate control has come quite a long ways since the days of dog sacrifice. Now, we just need to find refuge in an air conditioned place.
The Blue Jay of Happiness notes that industries and schools instituted months long vacations because the interiors of buildings were too hot. People were too uncomfortable to work efficiently and pupils couldn’t concentrate on their studies. Our culture still maintains the tradition of summer vacation despite a/c.