Friday, August 10, 2007

The History Of Windmills


A windmill is an engine powered by the wind to produce energy, often contained in a large building as in traditional post mills, smock mills and tower mills. The energy windmills produce can be used in many ways, traditionally for grinding grain or spices, pumping water, sawing wood or hammering seeds. Modern wind power machines are used for generating electricity, more commonly called wind turbines.

A windwheel operating an organ is described as early as the 1st century AD by Hero of Alexandria, marking probably the first instance of a wind powering machine in history. Vertical axle windmills were first used in eastern Persia (Sistan) by the 9th century AD as described by Muslim geographers. Horizontal axle windmills of the type generally used today were invented in Northwestern Europe in the 1180s.

The first windmills had long vertical shafts with rectangle shaped blades and appeared in Persia in the 9th century. The authenticity of an earlier anecdote of a windmill involving the second caliph Umar (634-644 AD) is questioned on the grounds of being a 10th century amendment. Made of six to twelve sails covered in reed matting or cloth material, these windmills were used to grind corn or draw up water, and quite different from the European versions. A similar type of vertical shaft windmill with rectangle blades, used for irrigation, and were found in 13th century China, introduced by the travels of Yel├╝ Chucai to Turkestan in 1219.

Fixed windmills, oriented to the prevailing wind were, for example, extensively used in the Cyclades islands of Greece. The economies of power and transport allowed the use of these 'offshore' mills for grinding grain transported from the mainland and flour returned. A 1/10th share of the flour was paid to the miller in return for his service. This type would mount triangular sails when in operation.

In North Western Europe, the horizontal-shaft or vertical windmill dates from the last quarter of the 12th century in the triangle of northern France, eastern England and Flanders. These earliest mills were used to grind cereals. The evidence at present is that the earliest type was the post mill, so named because of the large upright post on which the mill's main structure (the "body" or "buck") is balanced. By mounting the body this way, the mill is able to rotate to face the (variable) wind direction; an essential requirement for windmills to operate economically in North-Western Europe, where wind directions are various. By the end of the thirteenth century the masonry tower mill, on which only the timber cap rotated rather than the whole body of the mill, had been introduced. Due to the fact that only the cap of the tower mill needed to be turned the main structure could be made much taller, allowing the blades to be made longer, which enabled them to provide useful work even in low winds.

The familiar lattice style of windmill blades allowed the miller to attach cloth sails to the blades (while applying a brake). Trimming the sails allowed the windmill to turn at near the optimal speed in a large range of wind velocities, while the fantail was smaller and mounted at right angles to the main sails which automatically turns the heavy cap and main sails into the wind, was invented in England in 1745. The smock mill is a later variation of the tower mill, constructed of timber and originally developed in the sixteenth century for land drainage. With some subsequent development mills became versatile in windy regions for all kind of industry, most notably grain grinding mills, sawmills (late 16th century), threshing, and, by applying scoop wheels, Archimedes' screws, and piston pumps, pumping water either for land drainage or for water supply.

With the industrial revolution, the importance of windmills as primary industrial energy source was replaced by steam and internal combustion engines. But with the increasing environmental concern, and approaching limits to fossil fuel consumption, wind power has regained interest as a renewable energy source. This new generation of wind mills produce electric power and are more generally referred to as wind turbines. Take a look at the different kinds of windmills still standing all around the world at: http://www.windmillworld.com/

Research info provided by: www.wikipedia.org
Photo by Deryk Baumqarter

Now here's 2 poems that will put some wind in your sail:


"Favorite Cleaver" Sonnet

It all begins with a complimentary Mai Tai. A
series of green lights all the way to the bomb
shelter. Rubber trees or planted Ferns.
Candystripers on No Doz. Bleary storms.
Vandalized drainage ditches. A townhall lit-up
by artillery fire. Italian breadsticks. Hold the
teriyaki. Favorite cleavers of a chef. Or maybe
a feigned case of food poisoning. Social unrest.
Secret wiretaps. Jell-O wishing it were blood.
Smoke alarms. Drinking music. Ammunition
that sparks global arguments. A throat lined
with cactus. Empty liquor glasses shell-shocked.
A diagnoses that predicts the world may never
dance again. Sweat pouring down the shoulders
of night. Then too, it could be that lone patron
wondering what else to do with the little tropical
umbrella but spin it.


Provocative, But Is It A Documentary?

She says her favorite hobby is worry beads. But who
needs a good conversationalist if you've never
believed in father Xmas or if every word
bounces against the rubber dinghy
with the sun on your shoulders
and toes dangling in lake
water. Warm could be
socks wearing
tangerine
toast.
Every
lighthouse
could spark the
murderous thoughts
of a gray slate roof. Or a
Trojan horse could end-up with
a reclusive heart or a phantom of utopia
with tangled hair. All the metal signs warn of
high-voltage lines. Even ordinary fog turns colossal...

a syringe doing a nose
dive into blue veins...

a pile of leaves that
manipulates bureaucracy.

Then too, the dialogue could grow into a cross between a
mobster and an aristocrat or a list of hazards associated
with too much corrupt autumn. Whatever happens, she'll
claim she's always looked that way.

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