reached a desired state. Additionally, small cones or bars can be arranged to mechanically trigger kiln controls when the temperature rises enough for them to deform. Precise, consistent placement of large and small cones must be followed to ensure the proper temperature equivalent is being reached. Every effort needs to be made to always have the cone inclined at 8° from the vertical. Large cones must be mounted 2 inches above the plaque and small cones mounted 15/16 inches. With the cones having their own base, "self-supporting cones" eliminate errors with their mounting. Control of variability Pyrometric cones are sensitive measuring devices and it is important to users that they should remain consistent in the way that they react to heating. Cone manufacturers follow procedures to control variability (within batches and between batches) to ensure that cones of a given grade remain consistent in their properties over long periods. A number of national standards and an ISO standard have been published regarding pyrometric cones. Even though cones from different manufacturers can have relatively similar numbering systems, they are not identical in their characteristics. If a change is made from one manufacturer to another, then allowances for the differences can sometimes be necessary. History In 1782, Josiah Wedgwood created accurately scaled pyrometric device, with details published in the Philosophical Transactions of the Royal Society of London in 1782 (Vol. LXXII, part 2). This led him to be elected a fellow of the Royal Society. The modern form of the pyrometric cone was developed by Hermann Seger and first used to control the firing of porcelain wares at the Royal Porcelain Factory, Berlin (Königliche Porzellanmanufaktur, in 1886, where Seger was director. Seger cones are made by a small number of companies and the term is often used as a synonym for pyrometric cones. The Standard Pyrometric Cone Company was founded in Columbus, Ohio, by Edward J. Orton, Jr. in 1896 to manufacture pyrometric cones, and following his death a charitable trust established to operate the company, which is known Edward Orton Jr. Ceramic Foundation, or Orton Ceramic Foundation. Ceramic art A biennial ceramic art exhibition for small work, the Orton Cone Box Show, takes the Orton Cone company's pyrometric cone box as the size constraint for submissions. Temperature ranges The following temperature equivalents for pyrometric cones were retrieved from references in the External Links section. Notes References Hamer, Frank and Hamer, Janet