[little_john]

Here are links to what must be the most counter-intuitive experiment ever. These .JPG's are perhaps best downloaded and viewed at 100-150% in a graphics viewer such as Irfanview (imo).

Ok - these contain a description and results of an experiment conducted by Gaston Bonnier in 1890 which was written-up in the British Bee Journal the following year. The experiment was designed to establish whether one or more frames of pre-drawn wax comb OR a division board (sealed at the sides and top) was better at preventing heat loss.
As frames normally have gaps at their sides and tops, it would seem a no-brainer that they would allow more heat to leak past them than a sealed division board (aka partition or follower board). The results obtained here show that for all intents and purposes there's no discernible difference between them. Personally, I still find this difficult to accept - but the results speak for themselves.

There are other reasons for using such boards of course: to restrict the colony to a smaller area; and such boards will function as an effective queen excluder - but from a purely thermal retention point of view they would appear to offer little advantage over a frame of wax comb, if any. Counter-intuitive or what ?

Links can be found at: http://heretics-guide.atwebpages.com/beekxx.htm

LJ

 

[crofter]

LJ; 403 error on all links.

 

[Saltybee]

Take the bottom link and then the bottom link

 

[rwlaw]

Ya, the main links are bad, the link thru LJ’s site is good tho. Interesting article.

 

[Saltybee]

Take the bottom link and then the bottom link

 

[Saltybee]

I would have been wrong. I would add smooth surface v porous as a possibility. Wonder how reflective foil would turn out.

 

[crofter]

What constitutes a "division board"; what material and how thick? What would be the result if it were made of foamboard insulation? Yes and if it were foil faced foamboard?

 

[Saltybee]

The bottom of the frame was left open. If closed would the frame have proven superior? I read the story as being a honey frame, an empty drawn frame would provide as much food as a board and better insulation/ heat flow ( My belief).
Is the best division board a partial honey frame caulked around the sides?

Could it be that I have been doing it all wrong? Still.

 

[little_john]

Sorry about the duff links guys - they worked for me, but presumably that's because I have some kind of direct access. I thought it would save folks a little time ... duhhh.

C'mon guys - they didn't have reflective foil and foam board back in 1890 ! (not that anybody uses it for partition boards - I use whatever plywood is handy, around 1/2".)

The important result for me is that the gaps around the comb didn't leak enormous amounts of heat, which is what would reasonably have been expected. People like Quinby, and much later Cowan, used to get their knickers in a right twist about those 'evil' gaps around the frames. Some 'natural beekeepers' still do

LJ

 

[little_john]

The bottom of the frame was left open. If closed would the frame have proven superior?

They were both open at the bottom - the frame naturally, and the Division Board by deliberate construction (see the Summary, Point C) - so if you're going to close one at the bottom, then you need to close the other in a similar way to keep the comparison fair.
LJ

 

[crofter]

If they were both open at the bottom and beespace above the frame, convection would be the main transfer of heat. Reflective value would be comparatively small as would through the barrier conductivity. Bee space at the sides of the frame compared to none with the follower board would affect convective flow only marginally. Not surprised that the difference is quite small.

What is the takeaway?

 

[little_john]

If they were both open at the bottom and beespace above the frame, convection would be the main transfer of heat.

But they weren't, so it wasn't.

"All the frames were covered in woollen cloths" (p.216, right-hand column, 17th line from the bottom). These cloths are shown placed directly on top of the frames in Fig.1., and inferred in the summary at the end of the article where the author writes: "The heat produced [...] can be dissipated [...] 3. By the current of air produced at the bottom and sides of the hive." i.e. not via the top.

I agree that in normal use frames have gaps all around them (except at the top when a 'soft' inner cover is being used), but here Bonnier appears to have been as careful as possible to maintain the same conditions for both frames and division board.
'best
LJ

 

[Saltybee]

"careful as possible to maintain the same conditions for both frames and division board."
LJ, I appreciate your digging down for the details.
I do not think of today's normal use of a division board as allowing air to pass under and around. Not sure of the depth of meaning from these results today. Still have to admit I would not have made the correct prediction even given the air passages.

 

[Saltybee]

The advantage of a board over a frame is the ability to squeeze the ends of the football shaped cluster into a tighter and flatter cluster. The diagram looks like that was not done.

 

[little_john]

"careful as possible to maintain the same conditions for both frames and division board."
LJ, I appreciate your digging down for the details.
I do not think of today's normal use of a division board as allowing air to pass under and around. Not sure of the depth of meaning from these results today. Still have to admit I would not have made the correct prediction even given the air passages.

Fwiw - that's exactly how I use them - with 2" cut off the bottom - likewise the Bienenkiste Hive does. Some Russians/Ukrainians use two during winter, with the colony sandwiched between them. But - yes - I agree that many people do not use them like this ...

The advantage of a board over a frame is the ability to squeeze the ends of the football shaped cluster into a tighter and flatter cluster. The diagram looks like that was not done.

But he wasn't trying to manipulate the cluster in any way - he was only concerned with comparing the heat retention characteristics of a board vs. framed-combs. Indeed - in the second experiment he used a tank of hot glycerine as a heat source rather than a cluster of bees.
LJ