1946 INCUBATION - Then, Now

Most of you will know I am an inveterate collector of the old books on chicken keeping. Well, one of my other interests is collecting the old Popular Mechanics compendium annuals known as “Shop Notes.” I recently got one from 1946 and was surprised to see three articles on making your own still air incubator, chick brooder and a ‘how-to’ on building a proper poultry house. As you might imagine, they were quite thorough and innovative for the time, in ways rivaling that which is seen today.

Here then, for your edification, is an excerpt from the incubator section.

Make of it what you will… I hope you like it.

"...It is of greatest importance that you use the best egg obtainable. Eggs shipped from a distance should stand on their small end for 24 hours, to regain their normal condition.

To prepare the incubator, withdraw the egg tray and cover the bottom with several layers of paper. Replace tray in incubator without the eggs and adjust the thermostat to maintain a temperature of 102 degrees, and leave for 24 hours.

After warming up the incubator for 24 hours, fill the tray with eggs. They should fill all the space; keep the tray crowded with eggs, even if you need to put a block or piece of wood in the back of the tray to keep them close together.

Place a thermometer (incubator type only) to one side of the thermostat at the third or fourth row from the door.

After seven days in warm weather, remove the paper from beneath the eggs - 12 days in cold weather. Allow the eggs to absorb heat gradually, but do not change the adjustment of the thermostat from the setting you initially stabilized at.

The first week it should be set at 102 with white eggs, second and third week 103, fourth week 104, and during hatching 104 to 105.

For dark eggs, run 1 degree higher each week. Chickens require 21 days to hatch, but begin counting from the second day.

Starting on the fourth day, and twice each day thereafter, up to and including the eighteenth day, (room temp should be bout 65 degrees), remove and place the egg tray on top of the incubator and close the door. Lay aside some of the eggs from the center of the tray and roll he others back and forth, finally leaving them toward the center. Do the same with the eggs that were laid aside, finally placing them back, around the edges of the tray.

Leave all the eggs out until they feel cool to the cheek, or about 5-10 min. the first week, 10-15 min. the second week and 15-20 min. the third week. Just before hatching, cover the eggs with a porous woolen cloth, wrung out of warm water. This helps the chicks to break the shells. Remove the cloth once hatching starts.

Duck and goose eggs require more moisture than chicken eggs, and a tray of wet sand placed on the slats of the chick tray in addition to a water pan below, is recommended.

Top control moisture at desired temperature, keep the top ventilators closed for the first seven days, but the bottom ones half open. Wider opening of the bottom vents will increase moisture; wider opening of the top vents decreases it. Incorrect moisture conditions will result in a sticky or bloody hatch and also cause chicks to die in the shell.

The ideal place for an incubator is in a dry, warm, well-ventilated basement where the temperature is fairly even. Level the incubator.

After hatching, chicks should be left in the chick trays until they are thoroughly dry and have gained some strength. They should never be subjected to sudden changes of temperature.
When you remove chicks from the incubator to the brooder, carry them in a covered basket or carton lined with soft material.

PS If you have any of the old “Shop Notes” books you are willing to part with, indeed any of the old PM books from the 30’s -60’s, I’d like to hear from you.

some of that stuff sounds nuts to me put paper in take paper out wet eggs
its crazy

Wow, those temps are wicked high, wonder what their hatch rate was...

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I dunno. Im hoping to at least borrow some of those tips.
But I can assure you, this is pretty
normal stuff for the period with their still air units.
We balk because we're advised to use different numbers today, although Im certain a chicken has always been 106 degrees F in body temp.

They had thermometers back then as useful as anything we have now. 1946 wasn't the stone age and 102 then was the same 102 now. And these temps they suggest were progressive - did you catch that? They changed over the course of the incubation period.

There was also a serious amount of daily cooling going on with the eggs. We never hear that today, but there is some sound logc behind that practice.

Again, this was all standard practice back then and you gotta surmise that it worked.

I liked the wrung out woolen cloth bit the most. What few apply is the knowledge that by the time of the hatch, the chicks are fully formed. You aren't going to do much to affect them one way or the other at that stage.
I can see where the dampended cloth may actually help at the end, since they were using what we like to call the "Dry Incubation" method. Humidity control was mostly dependent on ambient influence and not measured or much modified in their plan.
We'll see.

Very neat, thank you for sharing!

It's quite fascinating...I wonder why they incubated white and "dark" eggs differently...

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That's a good question, one I DONT know the answer to. I've studied a lot of this old stuff and that bit was lost on me.

Something else I thought about was the temps quoted are air temps. These are invariably higher than actual, as any user of a water weasle will tell you.

I thought the difference in temps for the egg shell color was interesting. The temps sound high to us, but this is for still air incubating. I usually run my temps 101-103 for incubating in my still air, my hatches work much better this way then trying to balance that darn LG on 99-99.5 .

The rest of it sounded logical. The wet cloth would boost humidity at the hatch, which keeps the membrane wet thus making it "easier for the chicks to hatch". The cooling, although most likely impractical in today's incubation, simulates the "hen" getting of the nest to do her thing. So I think the cooling was used to keep the incubating as natural as possible.

The thing that threw me the most was the whole paper deal. What was that about, did it explain what the paper was for, Dave?

I thoroughly enjoyed reading and re-reading that, Dave. Thanks!

-Kim

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It didn't go into detail on the paper, no. WHat you saw was it.
Near as I can surmise, it has to do with holding humidity. The eggs respire, as we know, giving off moisture. Since this process is based on ambient humidity conditions, the paper prevents air circulation, and so would hold this respired moisture close to the eggs.
That's the best I can come up with. It is the first I recall seeing it in any of my old books - and I have a lot of old poultry books...

The rest iof the article deals with construction of the unit, so I didnt include that stuff. Some other interesting things:
It was insulated with 2 layers of corrugated board (cardboard),
had a double pane window,
a lower chick tray*
Could be made to run on electricity or kerosene.

* When the chicks begin hatching, you remove a section from the front of the egg tray, leaving it open across the front. As they hatch out, they naturally move towards the light from the window - and fall through the open section to a waiting tray below!

Thank you for this information.
This sort of clears up something for me.

I was giving an old old incubator. Along with it, I assumed are a couple of poultry thermo. that were factory pre-marked with 103 and 105 on it.
I couldn't figure out what the heck those temps. were all about until now.
So now I am wondering all over again as to what age this bator really is.

It looks like two huge round metal cake pans, one invert over the other with a tiny window in it.