Also known as "16x10"
Originally developed by Samuel Simmins as "The National Major" Hive in about 1884.
It has 16" x 10" frames in the brood box, hence the alternative name of "16x10", with 16" x 6" frames in the supers, both with short lugs.
Apparently the British Standard allowed for both top and bottom bee space, although bottom seems to be preferred by the major manufacturers. This allows boxes to be used with National hives, as the external dimensions are identical.
Only the Brood Box and Super, and their respective frames, are different. The other components being identical to the "National".
It is common for National supers to be used instead of the Commercial 16" x 6" version, owing to the lesser weight and bigger handholds of the former. Despite this it is common in Ireland for 16" x 6" Commercial supers to be used on National brood boxes! They make them cheaply from scrap or used timber, which makes sense because they are only exposed to the elemnts for a few weeks in the summer.
The addition of a 'Hamilton converter' on a National brood box enables the use of ten 16" x 10" Commercial brood frames at 90°. This is useful for those who have both frame types and for changing sizes.
In my opinion this hive is too large for non - prolific bees, but it is suitable for prolific bees, where is will compete with a Langstroth or "brood and a half".
For the keen woodworker the boxes are easier to make than the National, but for those who prefer non - prolific bees the Smith hive would be a better option, having the same amount of work to make it, but is a smaller hive.
I'm sorry, but I don't have any Commercial hive drawings to display or link to.