martes, 29 de mayo de 2007

The watermill

1 comentario:

jolabent27 dijo...

Drawings Numbers 18A,18B,18C, Middle-Earth, Watermill:
The conversion of corn into flour, which could be used to bake bread and cakes is also a very old art. The ancient civilisations used it thousands of year ago.
The first part of the process, after reaping, is to thresh the grain in order to separate the husk from the kernel, and this includes winnowing, which disposes of the husk.
In ancient times, and in some underdeveloped countries to-day, this is all done by hand. The corn is beaten vigorously against a suitable rock until the husk is separated, then it is placed on a large cloth, and two or more persons toss the cloth up and down in the wind until the lighter husk has all blown away, leaving the heavier grain on the cloth. The stems of the grain are used as straw for animal's bedding. I have done these operations myself.
The next phase is to grind the kernels into powder, that is, flour, and in the most primitive societies this was, and is, done by placing the kernels in a mortar formed of a hollowed-out log, and pounding them vigorously with a heavy wooden pestle until they are pulverised and so have become flour.
Later on in history came the development of Mills, driven by treadmills worked by animals, and then by wind or water.
Professor Tolkien describes the Watermill at Hobbiton, owned by the family Sandyman, and in Drawings 18A,18B, and 18C, I show a Watermill capable of supplying a fair-sized district with flour.
Drawing Number 18C, published here in this blog, shows a general view of the mill, millpond, dam, and sluices. Drawings Numbers 18A and 18B, available on request,show the Waterwheels and internal machinery of the Mill.
Basically, there are two types of Waterwheel, the undershot and the overshot. The undershot wheel is so designed that the water flows underneath the wheel, driving the wheelpaddles round by means of the force of the current of the river. The problem which arises with this type of wheel is that, if the force of the current is reduced by lack of rainfall, the available power provided by the wheel will also reduce, possibly to the point where the wheel will cease to turn at all.
The overshot wheel is so designed that the water, drawn from higher up the river, or stored in a mill-pond formed by a dam, is guided by sluices to a point above the millwheel, and falls into the buckets of the same, thereby driving the millwheel round by the force of the weight of the water in the buckets.
This is a more reliable and effective system, but it is much more expensive to intall.
However, it is also much more easily controlled by means of sluice-gates, which can be so adjusted as to provide exactly the amount of water required to drive the milling machinery at the speed called for by the Miller, and to avoid the risk of damage to the millwheel and other machinery in times of flood.
In the drawings, I describe the wheel, piers, sluices, and milling machinery, and have specified a double overshot millwheel in order to ensure an adequate supply of power to the machinery. In Drawing Number18C I describe the general appearance of the Mill, millpond,dam,sluices,sluice-gates,millwheel,and spillway.
Up until the middle 1950's the Watermill at Guildford in Surrey, England, which drew it's power from the River Wey, was still operating,and,for all I know, may even still be doing so. It is a Mill considerably larger than the one shewn in Drawing Number18C.
In the Mill described here for Hobbiton, the third floor is the Grain Floor, to which the threshed grain is brought up from carts by means of a hoist at the rear of the building. From there the grain is chuted down to the second, or Milling Floor, where it is ground into wholemeal flour by the millstones, and this flour is then chuted down to the first, or Finishing Floor, where it is bagged into sacks,and then loaded onto customer's carts when they come to call for it.
The higher floors are for storage and general use.
It will be noticed that the roof is thatched, and that there are no chimneys. The practical reason for this is that flour dust, mixed with air, is explosive by nature, which is why the old mills only worked in daylight. The expansive blast wave caused by an explosion would blow the thatched roof off, but leave the walls intact. It would also be of less pressure, which would increase the chances of survival among the workforce.
There is, of course, NO SMOKING!
in a flourmill!