Glassworks tower
A glassworks tower , also known as a smoke gas cone or English tower , is a shaft furnace up to 35 meters high that was used by glassworks in Europe for the production of glass during the 18th and 19th centuries . In Germany, the cone-shaped buildings were especially widespread in the area of the central Weser . The last two German copies are in the Gernheim glassworks near Petershagen and the Steinkrug glassworks near Hanover . The towers were based on Scottish and English models, where four examples are still preserved today. There, the sugar- loaf -like towers were called "hovel" or "howel", today as "glasscone".
Origin and decline
The time of the invention of the glassworks tower can no longer be precisely determined. The technique was already described and illustrated by Denis Diderot in Volume 10 of the Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers , published in 1772 .
The oldest examples of glass towers can be dated to the middle of the 18th century. No more towers were built after 1850. One of the reasons for discontinuing these buildings is the construction-related confinement of the rooms for the glassmakers . Industrial production with the introduction of the continuously operating furnace could also have played a role. Nevertheless, the existing glassworks towers remained in operation until the early 20th century, especially for smaller glass production lines. Unless the towers were demolished by the glassworks for business expansion, they often served as storage space.
The closure of the last still producing glassworks tower took place in 1972 in Alloa, Scotland, in the Clackmannanshire district , when the floor of the furnace collapsed.
Construction
Glassworks towers were between 13 and 35 meters high, their base area was about 10 to 25 meters in diameter. The upper circular opening to the smoke outlet had a diameter of about three meters, in some cases a short metal chimney was attached. In many cases, glassworks towers had several unevenly distributed door and window openings that were used to regulate the draft.
The towers were built in a cone shape from bricks , rubble stones or hewn sandstones . Depending on the construction height, the wall thickness in the lower area was about one meter or more. The stone foundation of the cone reached up to six meters into the ground. Enormous amounts of stone material were needed to build it. The still preserved tower of the British Lemington Glass Works (near Newcastle upon Tyne ) had 1.75 million bricks. A cone tower in Obernkirchen , about 20 meters high and no longer existing , had a stone mass of 1,110 m 3 and a weight of 2,800 tons.
functionality
In the lower area of the tower was the glassmaker's work area, the conical shape of the tower facilitated the extraction of smelter smoke . The functioning of the tower as a shaft furnace is based on the chimney effect . The hot combustion gases from the coal fire were directed upwards in the cone shape to the round opening. The suction effect of the air draft allows higher temperatures and shorter melting times to be achieved with better energy yield. The hearth with the glass melting furnace was on the floor of the glassworks tower. To control the air supply, all openings in the tower were closed and the air flowed in through the underground tunnel . Since the draft was important, glass towers similar to windmills were often built on hills. The semicircular openings on the sides of the towers, which can often be found, originate from masonry openings to which single-storey outbuildings with a gable roof were added. It contained stretching and cooling ovens for further glass processing.
Received towers
Germany
The following two examples of glassworks towers are still in Germany:
| Surname | place | Construction year | material | height | diameter | image |
|---|---|---|---|---|---|---|
| Gernheim glassworks | Petershagen - Ovenstädt | 1826 | Brick | 25 m | 15 m |
 |
| Glassworks Steinkrug | Bredenbeck - Steinkrug | 1839 | Sandstone | 13 m | 10 m |
 |
Great Britain
The following four towers have been preserved in Great Britain:
| Surname | place | Construction year | material | height | diameter | image |
|---|---|---|---|---|---|---|
| Catcliffe Glass Cone | Catcliffe, South Yorkshire | 1740 | Brick | 20 m |
 |
|
| Red House Cone | Wordsley, Metropolitan Borough of Dudley | 1790 | Brick | 27 m | 18 m |
 |
| Lemington Glass Cone | Lemington, Newcastle upon Tyne |
1797 | Brick | 35 m | 21 m |
 |
| Alloa Glass Cone | Alloa, Clackmannanshire | 1825 | Brick | 24 m |
|
France
The first glassworks towers in France belonged to the Royal Crystal Factory in Le Creusot , which was built for Marie Antoinette from 1787 . The two preserved towers are today part of the local glass castle.
No longer existing towers
The number of previously existing glassworks towers in Germany is no longer known, as the constructions often fell victim to the modernization of glassworks. The oldest glassworks tower in Germany is a no longer existing construction from 1758 in Essen-Steele . There is only one more recent drawing of her based on a lost painting.
In 1827 a glassworks tower was built in the Schauenstein glass factory in Obernkirchen . The establishment is believed to be due to influences from England via the then owner Caspar Hermann Heye . In 1842 a second glassworks tower was built on the site of the glass factory. In the 1960s, the towers gave way to newer operating buildings belonging to Heye Glas, which is now a production site for Ardagh Glass .
In Gersweiler in Saarland, the Sophiental glassworks had a glassworks tower in the 19th century, which was demolished in 1922 after storm damage.
A tower in Rotherham , UK , was demolished in 1946. In Monkwearmouth, Northern England, in the Sunderland district , a tower was in operation until 1959, but was demolished that year.
Based on the archaeological investigations that have been ongoing since 2011 until today (2017), it is assumed that the Klein Süntel glassworks had a glassworks tower.
literature
- Rudolf Günther: Smoke gas cones on old hut buildings , in: Glass technical reports from December 1961
Web links
- Historical photos of the glassworks towers in Obernkirchen
- Catcliffe Glass Cone as an article in the English Wikipedia
- Red House Cone as an article in the English Wikipedia
- Photos and construction drawings of the glassworks tower in Alloa, Scotland
- New references to glassworks architecture of the 19th century using the example of an unknown drawing of the Sophienthal glassworks in Gersweiler (pdf, 3.2 MB)