IN an 1877 book called The Poultry Yard and Market by Prof. Corbett, he cites that the Egyptians used "ovens" of wheat for incubator in temples dedicated to Isis. He goes on to say that the invention is attributed to the priests of Isis for the generation of more ducks than the typical broody hen could sit; pretty identical to our purposes today. Alas there is no record of how the ovens were constructed.
Corbett continues this thread, of "there is nothing new under the Sun" and finds that Emperor Constantine of the Byzantine Empire had "read" of these ovens and sent people to Egypt to find some and figure out their construction, realizing that a full stomach would make a happier populace; something Bonaparte epitomized i his epithet, An army travels on is stomach. Alas so does a populace as the Emperor was soon to find out.
Constantine's men found no record, other than holes in the earth leading some to believe that the Egyptians copied the Ostrich and let the sun's heat do its bidding. That unfortunately would not work in the more northern Istanbul except in the very warm days of summer and even then would need some protection from predators, errant pedestrians & inclement weather. Housing is the key, but then so is controlling the temperature.
Corbett himself tried housing the eggs with glass domes. No good as the glass was a great conductor of weather and when it was hot the inside shot up to 120F. When it was dark at night, the glass contracted and the heat left and the temperatures plummeted. Glass was out. Besides would have the Egyptians used such a pricey material? doubtful at best.
During the heydays of the Renaissance, when a whole rekindling of Classical times began in earnest, the Republics of Florence and Naples, built a series of these ovens. These, Professor Corbett, tells us are more like kilns, and built heavily into the ground, actually over a ditch beneath. The eggs were kept warm by the earth, and water was thrown upon it every so often, so that the dome did not overheat. Besides cooling down the kilns and the surrounding earth, the water would also serve of adding some humidity to the incubating eggs. Nice idea but on a large scale earth movers are required as Florence did not have readily the slaves of Egypt nor the space of the Nile Delta. Still it worked and both places hatched by the dozen and this allowed a lot more research into the duck and chicken to occur.
It wasn't until after the thermometer was invented by Galileo Galilei in 1592 that actually knowikng the correct temperature could be determined; before it was a practised eye like most of the natural sciences. But alas there was no correct scale of measurement that could be used reliably.
That changed when the Dutch physicist, Daniel Gabriel Fahrenheit in 1700–30 produced accurate mercury thermometers calibrated to a standard scale that ranged from 32°, the melting point of ice, to 96° for body temperature. The unit of temperature (degree) on the Fahrenheit temperature scale is 1/180 of the difference between the boiling (212°) and freezing points of water.
Celsius a scale made up of 100 degrees is attributed to the Swedish astronomer Anders Celsius, who developed it several years after Fahrenheit in 1742. Celsius used 0° for the boiling point of water and 100° for the melting point of snow, being in Sweden this made sense but this was later inverted to put 0° on the cold end and 100° on the hot end, and it was i that form it gained widespread use. Le Napoleon, him again, endorsed it as the French method and it was known simply as the centigrade scale until in 1948 the name was changed to the Celsius temperature scale.
Then in 1848 the British physicist William Thomson (later Lord Kelvin) proposed a system that used the degree Celsius keyed to absolute zero (−273.15 °C); the unit of this scale is now known as the kelvin while the Rankine scale employs the Fahrenheit degree keyed to absolute zero (−459.67 °F). (I'm a stalwart Fahrenheit fan btw).
So it was not until 1777 that a French physician, Bonnemain, amred with both a thermometer and the Celsius scale, was able to actually establish hatching ovens en masse, by heating them by circulating tubes of hot water. He was so good at controlling the temperature that he moved his business to Paris and was able to hatch out one thousand little chicks a day. While this sounds incredible, and it maybe, there are historical records it seems that show that Bonnemain was able to sell a good "abundance" of chickens every day of the year.
We do not know what chickens he used but in 1814 a major fire destroyed his establishment and so to recoup his losses, Dr Bonnemain, sold subscriptions to buy and build new ovens. Being ever the industrious Frenchman, he also sold a pamphlet describing his operation, but not mentioning the actual setup i.e. the temperatures for the water. Obviously Bonnemain was no fool, but nevertheless 30 years later, Monsieur Bir, brought his hatching box to the Jardin des Plantes in Paris for exhibition where he hatched, on site, 100 eggs.
No mention of his chickens either.
By 1853 Mr Cantallo, of England, was making incubators in London, all heated with lamps. Here we suppose that he was using his native Ligurian Chickens, i.e. the Leghorn, a known stalwart producer.
Twenty years later, a French American dentist, Dr Preterre, made an incubator in New York City and he showed it off at the Farmer's Club at the Cooper Institute (now part of the Smithsonian), March 1874. His method of heating would raise most people's eyebrows, he used horse manure and steam.
The key, and Prof Corbett did investigate this, is that the manure must be from horses fed with grain (not grass or hay)and it must be fresh, old rotting manure is good for the garden but not for the incubator.
