It's the same as a standard National but longer...takes 14 frames and a dummy board, which seems a bit stupid, why not just 14 frames? However I have abandoned using them, because I found the bees just didn't stretch the nest that far, so the outer two frames were fairly unused. I also had only 2 supers per hive which isn't enough and I wasn't able to get any more (I could have made some but decided to abandon for above reasons before I got round to it). The most useful thing about them now I find is the very wide spacing in the supers is handy for transporting frames for extraction and without spacers for storing frames in winter.
Frisbee
This is quite interesting ... my long hive has 14 x 12 frames and they have filled it out this year to about 13 frames ... they were a medium sized swarm in June and my frames were foundationless. The outer frames are used only for stores by the bees (but there is no queen excluder to prevent her from laying in them if she wanted).
So ... although you no longer use them I'm interested to know whether the outer frames were not used by the bees because the colony was not big enough or because you put supers on before the outer frames were filled ?
There is some evidence that 'modern' bees have been 'encouraged', 'bred' or 'acclimatised' to live in smaller colonies ... for beekeeper convenience. Splitting hives to discourage swarming and national sized brood boxes contributing to this situation.
Although, it seems to me that Finman is right about encouraging the establishment of BIG colonies ...
My long hive will allow 22 frames in a horizontal box and I currently have 10/11 seams of bees with a large amount of capped brood which, I assume, will give me a sizeable overwintering colony. My hope for next year is that this colony (assuming a good season) will expand to use the full potential 22 frames and if this happens I have plans for supering the hive. But ... if your experience with the Gale hive (and all 14 frames in the brood box not being worked) follows through to my hive then I am in trouble !!!
HENCE MY INTEREST !!!
PS: I suspect the dummy board is just there to allow it to be pulled out to permit easier frame manipulation ... quite a nice design aspect so that people cannot inadvertently stick in another frame and defeat the object of the dummy board.
A dummy board in a brood box of this size would be essential anyway to curtail the size of the brood area whilst the bees built out to the full size of the box so it's a clever idea for that reason as well.