Water-Mill Gears With Toothed Wheels

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Water-Mill Gears With Toothed Wheels

Postby Marcus Minucius Audens » Thu Sep 29, 2016 6:36 am

>>>> Greek - Roman Water Power #5 <<<<

>>> Water-Mill Gears With Toothed Wheels <<<

Vitrvius has provided a very clear description of how the horizontal drive shaft of the water-wheel is turned from a horizontal drive to a vertical drive. This explanation is taken from the Athenian Agora Mill as described. In addition, the author identifies the parts which make up this gearing complex. The first is the circular disk with teeth which is fastened to the horizontal drive shaft. This disk is called a “dentatum” and revolves in a vertical plane. The second is a similar circular disk with teeth which is fastened to a vertical shaft and revolves in a hoizontal plane. This disk is named the “item dentatum,” and is responsible for driving the vertical shaft which powers the millstone set.

There has been some disagreement between scholars as to the diameter of the “item dentatum” wheel. Some have thought that the second disk might have been reduced in size so as to speed up the revolutions of the millstone, but such an improvement would have been totally impossible, except with a highly powered overshot-wheel, which Vetruvius may not have been aware of. An undershot-wheel would not be able to rotate the millstone on even a 1 to 1 gear ratio basis.

Now it is supposed and hoped that a water-wheel would be used for a wider variety of uses than simply water-raising and grinding corn, however there is only one mention of such that provides any light to that hope. This is a very short and very teasing glimpse at another idea from history. This is a poem written by the rather strange author Ausonius, from the fourth century on the River Moselle. He is speaking in the poem about the River Erubius (Ruwar R.):

“ He, turning the millstones with a rapid whirling motion;
And drawing the screeching saws through smooth white stone,
Listens to the endless uproar from each of his banks (362-4)”

While this author is not totally clear in his meanings, the poem seems to be saying that water-wheel power was being utilized to saw stone. Another famous Roman author by the name of Pliny (Nat. Hist.36, 159) has mentioned in his writings that there are stones which can be cut with wood-saws and such stone was available here in this area, but several questions remain:

>> The stone was probably soapstone used for roofing tiles and such, not building walls;
>> How did the water-wheels “draw” the saws through stone?
>> “Trahere” might be a strange term for even an author as strange as Master Ausonius was, for the term describing a circular saw, even if such was known in those times;
>> Did the wheel have a cam and lever, or a crank and connecting-rod to push the saw back and forth?
In the vaccum of no evidence for any of the above, it is only guesswork as well as a regret that no written information has been found for that era.


>> J. G. Landels, “Engineering In the Ancient World,” (Univ. of Calif. Press, Berkeley, 1981);
>> Henry Hodges, J. Newcomer (Dwgs.), “ Technology In the Ancient World,” (Alfred A. Knopf, N.Y., 1970).

Respectfully Submitted;
Marcus Audens
Marcus Minucius Audens

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