Oh so fascinating! Someone just sent me a link to a patent granted by the U.S. Patent Office for a beehive that is eerily similar to the Flow hive but is made of metal. The inventor, Juan Garriga, lived in Spain and submitted the patent on August 8, 1939. The patent was approved on December 3, 1940.
The second and third paragraphs read as follows:
By use of the beehive cells according to my invention all the operations of extracting honey from the hive are greatly simplified by dispensing with manipulations in the interior of the hives with the result that the work of collecting the honey, which is long, fatiguing, and even dangerous, is converted into a short and easy operation, which can be performed by any person.
On the other hand the bees are not annoyed by the operations which have to be carried out in order to gather and store the honey, thus avoiding diminution in the amount of honey produced, all of which is to the benefit of the bee-keeper.
The hive works basically the same way as the Flow, by displacing the cells along the central plane of the comb and allowing the honey to drain out from both sides. When drained, the comb can be moved back into position. The diagrams even show tubes running from the hive into a container.
You may find this interesting; I certainly did. United States Patent US2223561