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Which windmill is which?

Poll #499309 Windmill typology

Which of these images shows a vertical windmill? The other is a horizontal windmill. There is no right answer.

Recreation drawing of early Persian windmill
Detail from image of Rhodes in Nuremberg Chronicle

The first image shows the earliest variety of windmill, which developed in Persia around the eigth century CE. They were built in natural windtunnels, the wind turning sails mounted on a vertical axle. The axle turned the millstones directly; no gearing was involved. (I can't find any really clear images of this kind of mill, but these might help make a bit more sense of what's happening in the drawing above.)

The second image shows a tower mill, a kind of mill which developed in the fourteenth century, and which derived from its antecedent, the post mill. The post mill developed in the eleventh century, in England. The post mill's entire structure pivots around a central support pole, while with the tower mill, only the building's cap pivots. Post mills were thus constructed out of wood, a lighter material, while tower mills generally came to be built out of stone, because the building's weight did not need to be supported on a single post. With both post mills and tower mills, the sails turn a horizontal post, with gearing to transfer the circular motion of the sails and post to the millstones. The image is a detail of the illustration of the city of Rhodes in the Nuremberg Chronicle.

Every scholar whose work I have read on the early history of windmills is consistent in which type of mill they refer to as vertical and which is horizontal, but they are not at all consistent as to which kind of mill is a vertical one and which is a horizontal one. The majority of historians call the post mill and tower mill vertical mills; but not all historians. Part of the problem lies in modern-day terminology, where the mills structured most like the post mill (i.e., with a horizontal axis) are regularly called horizontal mills. Most historians look at the overall building structure, while most modern mill builders look at the axle around which the sails turn when calling mills one thing or the other.

In my dissertation, I've dodged the entire question by referring to mills as having either a horizontal or vertical axle; that, at least, can be universally agreed upon.

I was wondering what other people, coming to the problem and the pictures for the first time, might choose as best embodying verticality or horizontality.


( 4 comments — Leave a comment )
May. 23rd, 2005 09:35 pm (UTC)
I think the second one is vertical .. in the first picture, I'm not convinced I know exactly what is going on ;-)

If I were you, though, I wouldn't dodge the question. I would make a claim and then in a footnote explain why you are calling one horizontal and one vertical. Then stick to whatever system you wish to use. You'll make the poor researchers who follow you happy, if you are the only one to actually clarify the confusion!
May. 23rd, 2005 09:42 pm (UTC)
Sorry about the first picture - it's a bit grotty and didn't shrink down well. There are very few images of the Persian mills since they're only known from digs, so all the images are reconstructions.

I'm happy to be decisive in a footnote, but I would rather not confuse people by getting involved with one use or the other, when I can be much more consistently clear by not doing either. The fewer words for which my readers need to go back to my definitions, the better. Frankly, there are just too many people using both terms for both kinds of mills; historical molinology is a pretty big field and I'm a tertiary player in it, especially since I tend to study how it's portrayed in art and literature, rather than looking at it in a more traditional history of technology or archaeological way.

It does need discussing though, since for all the books I've looked at on the history of windmills, and all the different ways scholars go on this subject, I've never seen any of them mention that this is an ongoing problem in the field. And it is.

Perhaps I'll be more assertive in my main text whenever I publish an article on windmills.
May. 23rd, 2005 10:17 pm (UTC)
I voted for numero 2, however, I'd agree with justinsomnia: make a decision as to which you're gonna call which, tehn make a footnate, explainign the difficulty of the porblem, and why you've gone teh way you've gone.
May. 24th, 2005 04:41 pm (UTC)
#1 horiz., #2 vert.
I agree with them, and I think you have dodged the dilemna nicely using the axle as a reference point. If historians have no uniformity in how they are labeling windmills, using a standard identifier (axle axis - say that 3x fast!) for your own articles is smart.
( 4 comments — Leave a comment )