A Cowl is a device used on a kiln to keep the weather out of, and induce a flow of air through, the kiln. Kilns are thermally insulated chambers or Ovens in which controlled temperature regimes are produced They are normally assosciated with oasts but can also be found on breweries (Letheringsett, Norfolk), maltings (Ware, Herts; Hadlow, Kent) and watermills (East Linton, East Lothian). oast or oast house is an example of Vernacular architecture in England, especially Kent and Sussex. A brewery is a dedicated building for the making of Beer, though beer can be made in the home and has been for much of beer's history Letheringsett is a village in the English County of Norfolk. It forms part of the civil parish of Letheringsett with Glanford along with the hamlet of Malting is a process applied to Cereal grains in which the grains are made to Germinate by soaking in water and are then quickly halted from germinating further WARE (1250 AM) is a Radio station broadcasting an Oldies format Hadlow is a village in the Medway valley of Tonbridge, Kent; it is in the Tonbridge and Malling district This article is about a type of structure For other locational uses see Milldam. East Linton is a town in East Lothian, Scotland, situated on the River Tyne and A1 road five Miles east of Haddington, with a [1][2]
Contents |
Construction
This section deals with the traditional cowls found on oasts, with particular reference to the South East. From the outside, a cowl appears to just sit on the roof of the kiln. High in the roof of the kiln is a beam spanning the centre, called the sprattle beam, this carries a bearing which the pintle on the bottom of the centre post sits in. For the freshwater fish see Gudgeon (fish. In general a gudgeon is a circular fitting often made of metal which is fixed onto some surface At the top of the kiln, the centre post passes through a two or three armed top stay iron. At the top of the centre post is carried the back board which carries an elm curb ring at the bottom, and one or two curb rings higher up on all except the smallest of cowls. Elms are Deciduous and Semi-deciduous Trees comprising the genus Ulmus, family Ulmaceae, found A tie beam could also be carried, either at each curb level, or just the bottom curb level, spanning the width of the cowl. The top of the backboard carries a shaped top plate to which the weatherboards were affixed. The whole is covered in tapered weatherboards, widest at the bottom and narrowest at the top. Weatherboarding is the Cladding or ‘ Siding ’ of a house consisting of long thin timber boards that overlap one another either vertically or horizontally on the Slotted through the centre post and attached to the back board is the distinctive finger which sometimes carried a motif. The finger assisted the turning of the cowl in light winds. Weatherboards would be attached to the cowl with nails made from copper. Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Cowls were usually painted white, although some were cream. The cowl is constructed so that when looking down vertically on a kiln, it covers the whole of the opening. It also covers some ⅔ to ¾ of the circumference of the kiln opening, the remaining section being open to allow air to vent from the kiln. The circumference is the distance around a closed Curve. Circumference is a kind of Perimeter. An illustration of a cowl and the cross-section of a kiln can be seen here. [3][4]
The size of cowls is expressed as height from top plate to base by width of kiln opening covered. Cowls varied in size from 7' by 5' (2. 13 by 1. 52 m) to 24' by 15' (7. 32 by 4. 57 m).
How does it work?
The cowl always has its back into the wind, with the finger pointing in the direction the wind is blowing to. Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) As the wind blows past the cowl, it creates a low pressure area inside the edge boards of the cowl. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface in the bottom of the kiln there are various openings, with these open a flow of air through the kiln is created, added to this is the heated air when a kiln is in use rising naturally as it is less dense than cold air. Convection in the most general terms refers to the movement of molecules within Fluids (i The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different [3]
Removal and repair
The building and maintenance of cowls was generally the job of a wheelwright. A wheelwright (or Wainwright) is a person who builds or repairs Wheels Making and balancing a wheel is skilled work. To remove a cowl, a cowl pole would be bolted to one of the main beams of the kiln, and the top would protrude from the top of the kiln. A rope would be passed over the pulley at the top of the cowl pole and tied around the cowl. A rope is a length of Fibers twisted or Braided together to improve strength for pulling and Connecting. A pulley (also called a sheave or block) is a Wheel with a groove between two Flanges around its Circumference The finger would be removed, and the coach bolt securing the centre post to the backboard undone. The cowl could then be lifted off the tenon at the top of the centre post and lowered down the kiln. Simple and strong the mortise and tenon joint has been used for millennia by Woodworkers around the world to join pieces of Wood, usually when the pieces Ropes were also tied at each end of the tie beam if present. The cowl could either be lowered inverted, or alternatively, a ladder would be placed against the kiln roof and the cowl be carried down by the wheelwright. A ladder is a vertical or inclined set of rungs or steps. There are two types rigid ladders that can be leaned against a vertical surface such as a Wall, and The weight being mainly taken by those in the kiln working on the rope. It was important to avoid damaging the kiln roof. Replacement was a reversal of the above process. A series of illustrations showing the process can be found here. The modern method involves using a mobile crane. [3]
Local variations
There were some variations in style amongst cowls.
Kent type
The standard cowl as described in the construction section. [3]
Sussex type
The Sussex type of cowl has an elongated top plate, giving the cowl a hooded appearance. Sussex type cowls could be found on Kent oasts, and Kent type cowls could be found on oasts in Sussex. Some oasts carried both types of cowl. [3]
West Midlands
The West Midlands type of cowl is similar to the Kent type, but without the top board. The weather boards meeting in a point. [5]
Other cowls
Cowls found outside the main hop growing areas were generally much cruder in construction and very different in looks. East Linton is a town in East Lothian, Scotland, situated on the River Tyne and A1 road five Miles east of Haddington, with a Often they were much squatter in appearance than oast cowls.
References
Sources
- Walton, Robin (1984). Oasts in Kent. Maidstone: Christine Swift. ISBN 0 9506977 3 7.
- Jones & Bell (1992). Oasthouses in Sussex and Kent. Chichester: Phillimore. ISBN 0 85033 818 2.
- (1988) A Pocketful of Hops. Bromyard: Bromyard Local History Society. ISBN 09502068 4 9.
External links
- Cowls A gallery of oast cowls.
- More cowls Another gallery of oast cowls
- Dude & Arnette Makers of cowls.
- Castle Mouldings Makers of cowls in fibreglass.
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic